Powertrain, generic (extended)

P2A65 Alternative Fuel Tank C Level Sensor Range/Performance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

For tank C this code reports a level that stays within the valid voltage window yet contradicts what happens to the tank. Examples are a reading that remains unchanged over many kilometres although tank C supplies the engine, no rise after a fill, or a level that disagrees with the pressure in a CNG cylinder. With LPG a float that sticks or a sender fitted at the wrong angle are likely; with calculated CNG levels the error usually sits in the pressure or temperature input. GM's Impala bulletin explains one harmless case: after a cold fill, the gauge may stay below full even though the tank is correctly filled. No manufacturer publishes P2A65; CARB requires rationality monitoring. Cross-check against the mechanical gauge at tank C.

Likely causes

Float in tank C sticking or sender mounted at a wrong angle (LPG)

Pressure or temperature input of tank C drifting (CNG)

Contact resistance shifting the level signal

Symptoms

Check engine light after several trips
Level for tank C frozen or illogical
Range estimate unreliable

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€80–700

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

alt fuel tank c level sensorwiring harnessafcm

References: law.cornell.edu, static.nhtsa.gov.