diff --git a/automotive/vehicle/2.1/Android.mk b/automotive/vehicle/2.1/Android.mk
index 095a1c7e44..2dfbefc164 100644
--- a/automotive/vehicle/2.1/Android.mk
+++ b/automotive/vehicle/2.1/Android.mk
@@ -18,9 +18,9 @@ LOCAL_JAVA_LIBRARIES := \
 
 
 #
-# Build types.hal (CommonIgnitionMonitors)
+# Build types.hal (DiagnosticFloatSensorIndex)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/CommonIgnitionMonitors.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/DiagnosticFloatSensorIndex.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -30,16 +30,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.CommonIgnitionMonitors
+        android.hardware.automotive.vehicle@2.1::types.DiagnosticFloatSensorIndex
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (CompressionIgnitionMonitors)
+# Build types.hal (DiagnosticIntegerSensorIndex)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/CompressionIgnitionMonitors.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/DiagnosticIntegerSensorIndex.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -49,16 +49,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.CompressionIgnitionMonitors
+        android.hardware.automotive.vehicle@2.1::types.DiagnosticIntegerSensorIndex
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (FuelSystemStatus)
+# Build types.hal (Obd2CommonIgnitionMonitors)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/FuelSystemStatus.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2CommonIgnitionMonitors.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -68,16 +68,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.FuelSystemStatus
+        android.hardware.automotive.vehicle@2.1::types.Obd2CommonIgnitionMonitors
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (FuelType)
+# Build types.hal (Obd2CompressionIgnitionMonitors)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/FuelType.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2CompressionIgnitionMonitors.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -87,16 +87,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.FuelType
+        android.hardware.automotive.vehicle@2.1::types.Obd2CompressionIgnitionMonitors
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (IgnitionMonitorKind)
+# Build types.hal (Obd2FuelSystemStatus)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/IgnitionMonitorKind.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2FuelSystemStatus.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -106,16 +106,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.IgnitionMonitorKind
+        android.hardware.automotive.vehicle@2.1::types.Obd2FuelSystemStatus
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (Obd2FloatSensorIndex)
+# Build types.hal (Obd2FuelType)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2FloatSensorIndex.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2FuelType.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -125,16 +125,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.Obd2FloatSensorIndex
+        android.hardware.automotive.vehicle@2.1::types.Obd2FuelType
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (Obd2IntegerSensorIndex)
+# Build types.hal (Obd2IgnitionMonitorKind)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2IntegerSensorIndex.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2IgnitionMonitorKind.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -144,16 +144,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.Obd2IntegerSensorIndex
+        android.hardware.automotive.vehicle@2.1::types.Obd2IgnitionMonitorKind
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (SecondaryAirStatus)
+# Build types.hal (Obd2SecondaryAirStatus)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/SecondaryAirStatus.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2SecondaryAirStatus.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -163,16 +163,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.SecondaryAirStatus
+        android.hardware.automotive.vehicle@2.1::types.Obd2SecondaryAirStatus
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (SparkIgnitionMonitors)
+# Build types.hal (Obd2SparkIgnitionMonitors)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/SparkIgnitionMonitors.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2SparkIgnitionMonitors.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -182,7 +182,7 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.SparkIgnitionMonitors
+        android.hardware.automotive.vehicle@2.1::types.Obd2SparkIgnitionMonitors
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
@@ -358,9 +358,9 @@ LOCAL_STATIC_JAVA_LIBRARIES := \
 
 
 #
-# Build types.hal (CommonIgnitionMonitors)
+# Build types.hal (DiagnosticFloatSensorIndex)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/CommonIgnitionMonitors.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/DiagnosticFloatSensorIndex.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -370,16 +370,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.CommonIgnitionMonitors
+        android.hardware.automotive.vehicle@2.1::types.DiagnosticFloatSensorIndex
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (CompressionIgnitionMonitors)
+# Build types.hal (DiagnosticIntegerSensorIndex)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/CompressionIgnitionMonitors.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/DiagnosticIntegerSensorIndex.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -389,16 +389,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.CompressionIgnitionMonitors
+        android.hardware.automotive.vehicle@2.1::types.DiagnosticIntegerSensorIndex
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (FuelSystemStatus)
+# Build types.hal (Obd2CommonIgnitionMonitors)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/FuelSystemStatus.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2CommonIgnitionMonitors.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -408,16 +408,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.FuelSystemStatus
+        android.hardware.automotive.vehicle@2.1::types.Obd2CommonIgnitionMonitors
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (FuelType)
+# Build types.hal (Obd2CompressionIgnitionMonitors)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/FuelType.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2CompressionIgnitionMonitors.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -427,16 +427,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.FuelType
+        android.hardware.automotive.vehicle@2.1::types.Obd2CompressionIgnitionMonitors
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (IgnitionMonitorKind)
+# Build types.hal (Obd2FuelSystemStatus)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/IgnitionMonitorKind.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2FuelSystemStatus.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -446,16 +446,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.IgnitionMonitorKind
+        android.hardware.automotive.vehicle@2.1::types.Obd2FuelSystemStatus
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (Obd2FloatSensorIndex)
+# Build types.hal (Obd2FuelType)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2FloatSensorIndex.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2FuelType.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -465,16 +465,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.Obd2FloatSensorIndex
+        android.hardware.automotive.vehicle@2.1::types.Obd2FuelType
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (Obd2IntegerSensorIndex)
+# Build types.hal (Obd2IgnitionMonitorKind)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2IntegerSensorIndex.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2IgnitionMonitorKind.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -484,16 +484,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.Obd2IntegerSensorIndex
+        android.hardware.automotive.vehicle@2.1::types.Obd2IgnitionMonitorKind
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (SecondaryAirStatus)
+# Build types.hal (Obd2SecondaryAirStatus)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/SecondaryAirStatus.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2SecondaryAirStatus.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -503,16 +503,16 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.SecondaryAirStatus
+        android.hardware.automotive.vehicle@2.1::types.Obd2SecondaryAirStatus
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
 
 #
-# Build types.hal (SparkIgnitionMonitors)
+# Build types.hal (Obd2SparkIgnitionMonitors)
 #
-GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/SparkIgnitionMonitors.java
+GEN := $(intermediates)/android/hardware/automotive/vehicle/V2_1/Obd2SparkIgnitionMonitors.java
 $(GEN): $(HIDL)
 $(GEN): PRIVATE_HIDL := $(HIDL)
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/types.hal
@@ -522,7 +522,7 @@ $(GEN): PRIVATE_CUSTOM_TOOL = \
         -Ljava \
         -randroid.hardware:hardware/interfaces \
         -randroid.hidl:system/libhidl/transport \
-        android.hardware.automotive.vehicle@2.1::types.SparkIgnitionMonitors
+        android.hardware.automotive.vehicle@2.1::types.Obd2SparkIgnitionMonitors
 
 $(GEN): $(LOCAL_PATH)/types.hal
 	$(transform-generated-source)
diff --git a/automotive/vehicle/2.1/default/common/include/vhal_v2_1/Obd2SensorStore.h b/automotive/vehicle/2.1/default/common/include/vhal_v2_1/Obd2SensorStore.h
index 6c44626d12..8000695543 100644
--- a/automotive/vehicle/2.1/default/common/include/vhal_v2_1/Obd2SensorStore.h
+++ b/automotive/vehicle/2.1/default/common/include/vhal_v2_1/Obd2SensorStore.h
@@ -38,12 +38,12 @@ public:
                     size_t numVendorFloatSensors);
 
     // Stores an integer-valued sensor.
-    V2_0::StatusCode setIntegerSensor(Obd2IntegerSensorIndex index, int32_t value);
+    V2_0::StatusCode setIntegerSensor(DiagnosticIntegerSensorIndex index, int32_t value);
     // Stores an integer-valued sensor.
     V2_0::StatusCode setIntegerSensor(size_t index, int32_t value);
 
     // Stores a float-valued sensor.
-    V2_0::StatusCode setFloatSensor(Obd2FloatSensorIndex index, float value);
+    V2_0::StatusCode setFloatSensor(DiagnosticFloatSensorIndex index, float value);
     // Stores a float-valued sensor.
     V2_0::StatusCode setFloatSensor(size_t index, float value);
 
diff --git a/automotive/vehicle/2.1/default/common/src/Obd2SensorStore.cpp b/automotive/vehicle/2.1/default/common/src/Obd2SensorStore.cpp
index f4c63a9544..8705e00b4c 100644
--- a/automotive/vehicle/2.1/default/common/src/Obd2SensorStore.cpp
+++ b/automotive/vehicle/2.1/default/common/src/Obd2SensorStore.cpp
@@ -56,9 +56,12 @@ const std::vector<uint8_t>& Obd2SensorStore::BitmaskInVector::getBitmask() const
 
 Obd2SensorStore::Obd2SensorStore(size_t numVendorIntegerSensors,
                                  size_t numVendorFloatSensors) {
+        using V2_0::toInt;
         // because the last index is valid *inclusive*
-        const size_t numSystemIntegerSensors = V2_0::toInt(Obd2IntegerSensorIndex::LAST_SYSTEM_INDEX)+1;
-        const size_t numSystemFloatSensors = V2_0::toInt(Obd2FloatSensorIndex::LAST_SYSTEM_INDEX)+1;
+        const size_t numSystemIntegerSensors =
+            toInt(DiagnosticIntegerSensorIndex::LAST_SYSTEM_INDEX)+1;
+        const size_t numSystemFloatSensors =
+            toInt(DiagnosticFloatSensorIndex::LAST_SYSTEM_INDEX)+1;
         mIntegerSensors = std::vector<int32_t>(
             numSystemIntegerSensors+numVendorIntegerSensors, 0);
         mFloatSensors = std::vector<float>(
@@ -66,11 +69,11 @@ Obd2SensorStore::Obd2SensorStore(size_t numVendorIntegerSensors,
         mSensorsBitmask.resize(mIntegerSensors.size()+mFloatSensors.size());
 }
 
-V2_0::StatusCode Obd2SensorStore::setIntegerSensor(Obd2IntegerSensorIndex index,
+V2_0::StatusCode Obd2SensorStore::setIntegerSensor(DiagnosticIntegerSensorIndex index,
     int32_t value) {
     return setIntegerSensor(V2_0::toInt(index), value);
 }
-V2_0::StatusCode Obd2SensorStore::setFloatSensor(Obd2FloatSensorIndex index,
+V2_0::StatusCode Obd2SensorStore::setFloatSensor(DiagnosticFloatSensorIndex index,
     float value) {
     return setFloatSensor(V2_0::toInt(index), value);
 }
diff --git a/automotive/vehicle/2.1/default/impl/vhal_v2_1/EmulatedVehicleHal.cpp b/automotive/vehicle/2.1/default/impl/vhal_v2_1/EmulatedVehicleHal.cpp
index 4faccbd999..568d62343d 100644
--- a/automotive/vehicle/2.1/default/impl/vhal_v2_1/EmulatedVehicleHal.cpp
+++ b/automotive/vehicle/2.1/default/impl/vhal_v2_1/EmulatedVehicleHal.cpp
@@ -37,85 +37,86 @@ namespace impl {
 static std::unique_ptr<Obd2SensorStore> fillDefaultObd2Frame(
         size_t numVendorIntegerSensors,
         size_t numVendorFloatSensors) {
+    using V2_0::toInt;
     std::unique_ptr<Obd2SensorStore> sensorStore(new Obd2SensorStore(
             numVendorIntegerSensors, numVendorFloatSensors));
 
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::FUEL_SYSTEM_STATUS,
-        V2_0::toInt(FuelSystemStatus::CLOSED_LOOP));
+        DiagnosticIntegerSensorIndex::FUEL_SYSTEM_STATUS,
+        toInt(Obd2FuelSystemStatus::CLOSED_LOOP));
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::MALFUNCTION_INDICATOR_LIGHT_ON, 0);
+        DiagnosticIntegerSensorIndex::MALFUNCTION_INDICATOR_LIGHT_ON, 0);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::IGNITION_MONITORS_SUPPORTED,
-        V2_0::toInt(IgnitionMonitorKind::SPARK));
-    sensorStore->setIntegerSensor(Obd2IntegerSensorIndex::IGNITION_SPECIFIC_MONITORS,
-        CommonIgnitionMonitors::COMPONENTS_AVAILABLE |
-        CommonIgnitionMonitors::MISFIRE_AVAILABLE |
-        SparkIgnitionMonitors::AC_REFRIGERANT_AVAILABLE |
-        SparkIgnitionMonitors::EVAPORATIVE_SYSTEM_AVAILABLE);
+        DiagnosticIntegerSensorIndex::IGNITION_MONITORS_SUPPORTED,
+        toInt(Obd2IgnitionMonitorKind::SPARK));
+    sensorStore->setIntegerSensor(DiagnosticIntegerSensorIndex::IGNITION_SPECIFIC_MONITORS,
+        Obd2CommonIgnitionMonitors::COMPONENTS_AVAILABLE |
+        Obd2CommonIgnitionMonitors::MISFIRE_AVAILABLE |
+        Obd2SparkIgnitionMonitors::AC_REFRIGERANT_AVAILABLE |
+        Obd2SparkIgnitionMonitors::EVAPORATIVE_SYSTEM_AVAILABLE);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::INTAKE_AIR_TEMPERATURE, 35);
+        DiagnosticIntegerSensorIndex::INTAKE_AIR_TEMPERATURE, 35);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::COMMANDED_SECONDARY_AIR_STATUS,
-        V2_0::toInt(SecondaryAirStatus::FROM_OUTSIDE_OR_OFF));
+        DiagnosticIntegerSensorIndex::COMMANDED_SECONDARY_AIR_STATUS,
+        toInt(Obd2SecondaryAirStatus::FROM_OUTSIDE_OR_OFF));
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::NUM_OXYGEN_SENSORS_PRESENT, 1);
+        DiagnosticIntegerSensorIndex::NUM_OXYGEN_SENSORS_PRESENT, 1);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::RUNTIME_SINCE_ENGINE_START, 500);
+        DiagnosticIntegerSensorIndex::RUNTIME_SINCE_ENGINE_START, 500);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::DISTANCE_TRAVELED_WITH_MALFUNCTION_INDICATOR_LIGHT_ON, 0);
+        DiagnosticIntegerSensorIndex::DISTANCE_TRAVELED_WITH_MALFUNCTION_INDICATOR_LIGHT_ON, 0);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::WARMUPS_SINCE_CODES_CLEARED, 51);
+        DiagnosticIntegerSensorIndex::WARMUPS_SINCE_CODES_CLEARED, 51);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::DISTANCE_TRAVELED_SINCE_CODES_CLEARED, 365);
+        DiagnosticIntegerSensorIndex::DISTANCE_TRAVELED_SINCE_CODES_CLEARED, 365);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::ABSOLUTE_BAROMETRIC_PRESSURE, 30);
+        DiagnosticIntegerSensorIndex::ABSOLUTE_BAROMETRIC_PRESSURE, 30);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::CONTROL_MODULE_VOLTAGE, 12);
+        DiagnosticIntegerSensorIndex::CONTROL_MODULE_VOLTAGE, 12);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::AMBIENT_AIR_TEMPERATURE, 18);
+        DiagnosticIntegerSensorIndex::AMBIENT_AIR_TEMPERATURE, 18);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::MAX_FUEL_AIR_EQUIVALENCE_RATIO, 1);
+        DiagnosticIntegerSensorIndex::MAX_FUEL_AIR_EQUIVALENCE_RATIO, 1);
     sensorStore->setIntegerSensor(
-        Obd2IntegerSensorIndex::FUEL_TYPE, V2_0::toInt(FuelType::GASOLINE));
+        DiagnosticIntegerSensorIndex::FUEL_TYPE, V2_0::toInt(Obd2FuelType::GASOLINE));
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::CALCULATED_ENGINE_LOAD, 0.153);
+        DiagnosticFloatSensorIndex::CALCULATED_ENGINE_LOAD, 0.153);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::SHORT_TERM_FUEL_TRIM_BANK1, -0.16);
+        DiagnosticFloatSensorIndex::SHORT_TERM_FUEL_TRIM_BANK1, -0.16);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::LONG_TERM_FUEL_TRIM_BANK1, -0.16);
+        DiagnosticFloatSensorIndex::LONG_TERM_FUEL_TRIM_BANK1, -0.16);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::SHORT_TERM_FUEL_TRIM_BANK2, -0.16);
+        DiagnosticFloatSensorIndex::SHORT_TERM_FUEL_TRIM_BANK2, -0.16);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::LONG_TERM_FUEL_TRIM_BANK2, -0.16);
+        DiagnosticFloatSensorIndex::LONG_TERM_FUEL_TRIM_BANK2, -0.16);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::INTAKE_MANIFOLD_ABSOLUTE_PRESSURE, 7.5);
+        DiagnosticFloatSensorIndex::INTAKE_MANIFOLD_ABSOLUTE_PRESSURE, 7.5);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::ENGINE_RPM, 1250.);
+        DiagnosticFloatSensorIndex::ENGINE_RPM, 1250.);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::VEHICLE_SPEED, 40.);
+        DiagnosticFloatSensorIndex::VEHICLE_SPEED, 40.);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::TIMING_ADVANCE, 2.5);
+        DiagnosticFloatSensorIndex::TIMING_ADVANCE, 2.5);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::THROTTLE_POSITION, 19.75);
+        DiagnosticFloatSensorIndex::THROTTLE_POSITION, 19.75);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::OXYGEN_SENSOR1_VOLTAGE, 0.265);
+        DiagnosticFloatSensorIndex::OXYGEN_SENSOR1_VOLTAGE, 0.265);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::FUEL_TANK_LEVEL_INPUT, 0.824);
+        DiagnosticFloatSensorIndex::FUEL_TANK_LEVEL_INPUT, 0.824);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::EVAPORATION_SYSTEM_VAPOR_PRESSURE, -0.373);
+        DiagnosticFloatSensorIndex::EVAPORATION_SYSTEM_VAPOR_PRESSURE, -0.373);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::CATALYST_TEMPERATURE_BANK1_SENSOR1, 190.);
+        DiagnosticFloatSensorIndex::CATALYST_TEMPERATURE_BANK1_SENSOR1, 190.);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::RELATIVE_THROTTLE_POSITION, 3.);
+        DiagnosticFloatSensorIndex::RELATIVE_THROTTLE_POSITION, 3.);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::ABSOLUTE_THROTTLE_POSITION_B, 0.306);
+        DiagnosticFloatSensorIndex::ABSOLUTE_THROTTLE_POSITION_B, 0.306);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::ACCELERATOR_PEDAL_POSITION_D, 0.188);
+        DiagnosticFloatSensorIndex::ACCELERATOR_PEDAL_POSITION_D, 0.188);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::ACCELERATOR_PEDAL_POSITION_E, 0.094);
+        DiagnosticFloatSensorIndex::ACCELERATOR_PEDAL_POSITION_E, 0.094);
     sensorStore->setFloatSensor(
-        Obd2FloatSensorIndex::COMMANDED_THROTTLE_ACTUATOR, 0.024);
+        DiagnosticFloatSensorIndex::COMMANDED_THROTTLE_ACTUATOR, 0.024);
 
     return sensorStore;
 }
diff --git a/automotive/vehicle/2.1/types.hal b/automotive/vehicle/2.1/types.hal
index cea7f1bfc7..e5f94113a3 100644
--- a/automotive/vehicle/2.1/types.hal
+++ b/automotive/vehicle/2.1/types.hal
@@ -260,8 +260,8 @@ enum VehicleProperty: @2.0::VehicleProperty {
       | VehicleArea:GLOBAL),
 };
 
-/** The status of a fuel system as described by the OBD2 specification. */
-enum FuelSystemStatus : int32_t {
+/** The status of the vehicle's fuel system. */
+enum Obd2FuelSystemStatus : int32_t {
   OPEN_INSUFFICIENT_ENGINE_TEMPERATURE = 1,
   CLOSED_LOOP = 2,
   OPEN_ENGINE_LOAD_OR_DECELERATION = 4,
@@ -270,13 +270,13 @@ enum FuelSystemStatus : int32_t {
 };
 
 /** Defines which ignition monitors are available to be read. */
-enum IgnitionMonitorKind : int32_t {
+enum Obd2IgnitionMonitorKind : int32_t {
   SPARK = 0,
   COMPRESSION = 1,
 };
 
 /** These ignition monitors are common to both SPARK and COMPRESSION. */
-enum CommonIgnitionMonitors : int32_t {
+enum Obd2CommonIgnitionMonitors : int32_t {
   COMPONENTS_AVAILABLE = 0x1 << 0,
   COMPONENTS_INCOMPLETE = 0x1 << 1,
 
@@ -288,7 +288,7 @@ enum CommonIgnitionMonitors : int32_t {
 };
 
 /** Ignition monitors available for SPARK vehicles. */
-enum SparkIgnitionMonitors : CommonIgnitionMonitors {
+enum Obd2SparkIgnitionMonitors : Obd2CommonIgnitionMonitors {
   EGR_AVAILABLE = 0x1 << 6,
   EGR_INCOMPLETE = 0x1 << 7,
 
@@ -315,7 +315,7 @@ enum SparkIgnitionMonitors : CommonIgnitionMonitors {
 };
 
 /** Ignition monitors only available for COMPRESSION vehicles. */
-enum CompressionIgnitionMonitors : CommonIgnitionMonitors {
+enum Obd2CompressionIgnitionMonitors : Obd2CommonIgnitionMonitors {
   EGR_OR_VVT_AVAILABLE = 0x1 << 6,
   EGR_OR_VVT_INCOMPLETE = 0x1 << 7,
 
@@ -335,14 +335,16 @@ enum CompressionIgnitionMonitors : CommonIgnitionMonitors {
   NMHC_CATALYST_INCOMPLETE = 0x1 << 17,
 };
 
-enum SecondaryAirStatus : int32_t {
+/** The status of the vehicle's secondary air system. */
+enum Obd2SecondaryAirStatus : int32_t {
   UPSTREAM = 1,
   DOWNSTREAM_OF_CATALYCIC_CONVERTER = 2,
   FROM_OUTSIDE_OR_OFF = 4,
   PUMP_ON_FOR_DIAGNOSTICS = 8,
 };
 
-enum FuelType : int32_t {
+/** The fuel type(s) supported by a vehicle. */
+enum Obd2FuelType : int32_t {
   NOT_AVAILABLE = 0,
   GASOLINE = 1,
   METHANOL = 2,
@@ -376,7 +378,7 @@ enum FuelType : int32_t {
  * expect a comment by the property definition describing the enum to look at for the mapping.
  * Any value greater than the last reserved index is available to vendors to map their extensions.
  */
-enum Obd2IntegerSensorIndex : int32_t {
+enum DiagnosticIntegerSensorIndex : int32_t {
   /** refer to FuelSystemStatus for a description of this value. */
   FUEL_SYSTEM_STATUS = 0,
   MALFUNCTION_INDICATOR_LIGHT_ON = 1,
@@ -431,7 +433,7 @@ enum Obd2IntegerSensorIndex : int32_t {
  * The ordering of the values is taken from the OBD2 specification.
  * Any value greater than the last reserved index is available to vendors to map their extensions.
  */
-enum Obd2FloatSensorIndex : int32_t {
+enum DiagnosticFloatSensorIndex : int32_t {
   CALCULATED_ENGINE_LOAD = 0,
   ENGINE_COOLANT_TEMPERATURE = 1,
   SHORT_TERM_FUEL_TRIM_BANK1 = 2,