Fuel and air

P01A2 — Alternative Fuel Tank A Pressure Sensor Erratic Signal

Severity: medium Drive with care, to a shop

What P01A2 means

The PCM monitors the pressure sensor on alternative fuel tank A (such as CNG, LPG or another gaseous fuel in a bi-fuel setup). P01A2 sets when the sensor signal jumps, drops out or doesn't make sense for the conditions. It usually points to a poor connection or a failing sensor rather than a real, rapid pressure change.

Symptoms

  • Check Engine light on
  • Inaccurate gas pressure or level readings
  • Vehicle won't switch to alternative fuel or forces gasoline mode
  • Higher gasoline use because gas mode is disabled
  • Fault that comes and goes

Possible causes

  1. Failed alternative fuel tank A pressure sensor
  2. Corroded, loose or broken sensor connector
  3. Damaged, chafed or wet wiring harness
  4. Signal wire shorted to ground or power
  5. Tank or fuel line problem such as a leak or damage
  6. PCM or gas control module fault (rare)

How to diagnose

  1. Read all codes and freeze frame data to see when the fault sets
  2. Inspect the sensor, connector and harness for corrosion, moisture, chafing or loose locks
  3. Check for gas odor and test fittings for leaks with a gas detector or leak solution
  4. Wiggle the harness and connector with the engine running while watching sensor data on a scan tool
  5. Test sensor 5V supply, ground and signal with a multimeter using the factory wiring diagram
  6. Compare the reading to a known-good pressure gauge
  7. If wiring is good, replace the sensor and clear the code
  8. If the code returns, check the PCM or gas control module

Common fixes

  • Clean or replace the corroded connector
  • Repair or replace the damaged section of wiring
  • Replace the alternative fuel tank A pressure sensor
  • Have a qualified shop repair any tank or line leak or damage
  • Reprogram or replace the PCM if a fault is confirmed

Questions and answers

Can I drive with P01A2?

Usually yes, particularly on gasoline, but have it checked soon. If you smell gas, stop and don't use the gas system until it's inspected.

What most often causes P01A2?

Most often a bad connection or damaged wiring at the sensor, less often the sensor itself. Inspect the harness before buying parts.

Can I just clear the code?

You can, but it will return if the cause remains. Intermittent faults often reappear with vibration or moisture.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.