Powertrain, generic · Fuel and air metering

P01A2 Alternative Fuel Tank A Pressure Sensor Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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.

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

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

Repair estimate

DifficultyHardWorkshop job
Parts and labour€120–600
Time1–3 h

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

Parts involved

alternative fuel tank pressure sensorgas pressure regulatorsensor wiring

Related codes

P019EP019FP01A0P01A1P01AAP01AF

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