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. P01A2 covers brief dropouts or jumps in the signal – usually a loose contact or a harness chafing along the gas line or underbody. 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.
High severity. Can I keep driving?If you smell gas, do not keep driving or start the engine: move away and call for assistance. With no smell, drive moderately to an authorized shop.
Symptoms
- 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
Most likely causes
- Loose contact or corrosion at the connector, wire broken by vibration
- Harness chafed along the gas line or underbody
- Sensor unstable internally
- Poor ground point or interference
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
- It affects emissions.
What each character of P01A2 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 1: Air and fuel
- A2: Specific fault in that system
Frequently asked questions
Can I keep driving with code P01A2?
If you smell gas, do not keep driving or start the engine: move away and call for assistance. With no smell, drive moderately to an authorized shop.
What causes code P01A2?
The most common causes are: loose contact or corrosion at the connector, wire broken by vibration; harness chafed along the gas line or underbody; sensor unstable internally.
Related codes
- P019EAlternative Fuel Tank A Pressure Sensor Circuit
- P019FAlternative Fuel Tank A Pressure Sensor Performance
- P01A0Alternative Fuel Tank A Pressure Sensor Circuit Low
- P01A1Alternative Fuel Tank A Pressure Sensor Circuit High
- P01AAAlternative Fuel Tank Temperature Sensor Circuit
- P01AFAlternative Fuel Tank A Level Sensor Circuit
Sources
- law.cornell.edu: 13 CCR 1968.2
- static.nhtsa.gov: MC 10114282 9999
- static.nhtsa.gov: INRD PE08063 33504P
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.