P01A1Alternative Fuel Tank A Pressure Sensor Circuit High
- 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 that run on a gaseous alternative fuel – compressed natural gas (CNG) or LPG – either as bi-fuel models alongside petrol (for example GM's 2015–2016 Impala Bi-Fuel or 2013–2016 Silverado/Sierra 2500HD) or as dedicated gas engines. CNG is stored at up to about 250 bar (3600 psi); a regulator reduces it to a few bar for the gas rail and injectors. The tank pressure sensor A sits at or in the regulator; together with the tank temperature it gives the gas level, and it decides whether gas operation is possible. P01A1 means the signal voltage is above its upper limit – typically an open sensor ground or a signal wire shorted to 5 V or battery voltage. Typical reaction: gas operation is blocked and a bi-fuel vehicle switches to petrol. No manufacturer document naming exactly this code was found; GM's bulletins only state that faults are reported like on petrol models. 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
- Check engine light on
- Gas level gauge wrong, jumping or showing empty
- Gas operation blocked or automatic switch to petrol
- Dedicated gas engines: limp mode or starting problems possible
- Likely causes
- LikelySensor ground wire open
- PossibleSignal wire shorted to 5 V reference or battery voltage
- PossibleTank pressure sensor faulty internally
- RareControl module faulty
- 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: €120 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.