P01AAAlternative Fuel Tank Temperature Sensor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- These codes only apply to vehicles with a gaseous alternative fuel – compressed natural gas (CNG) or LPG – as bi-fuel models alongside petrol or as dedicated gas engines; on bi-fuel vehicles a fault usually blocks gas operation and the vehicle runs on petrol. The tank temperature sensor is an NTC thermistor: with CNG there is no float, so the gas level is calculated from tank pressure and tank temperature (GM: full at about 3600 psi at 21 °C, empty at about 400–500 psi). On GM's 2015 Impala Bi-Fuel the sensor is built into the tank and cannot be replaced separately. P01AA is the general circuit fault of this sensor without telling low from high. No manufacturer document using exactly this code was found; the description rests on CARB, which treats such vehicles like petrol engines for model years 2004–2018, and on the documented system design.
- What you may notice
- Stored fault code (warning light depending on system)
- Gas level display wrong
- Gas operation blocked, switch to petrol
- Likely causes
- LikelyConnector or wiring of the tank temperature sensor open, corroded or chafed
- PossibleSensor faulty
- RareGas module, CAN link or engine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.