Fuel and air

P01A0 — Alternative Fuel Tank A Pressure Sensor Circuit Low

Severity: medium Drive with care, to a shop

What P01A0 means

The engine control module monitors the signal voltage of the pressure sensor on alternative fuel tank A, typically a CNG or LPG tank. The sensor normally outputs a voltage that rises with tank pressure. When the signal falls below the expected range, the module sets P01A0 and turns on the check engine light. The cause can be the sensor, its wiring, or genuinely low tank pressure.

Symptoms

  • Check engine light on
  • Rough idle
  • Higher fuel consumption
  • Unstable running on alternative fuel or switching to gasoline
  • Wrong tank pressure or level readings
  • Reduced power

Possible causes

  1. Failed alternative fuel tank pressure sensor
  2. Open circuit or short to ground in the signal wire
  3. Corroded or loose sensor connector
  4. Missing 5 V reference supply to the sensor
  5. Genuinely low tank pressure (empty tank, leak, faulty tank valve)
  6. Rarely, a faulty ECM

How to diagnose

  1. Scan all codes and freeze frame data and note any other fuel system codes
  2. Confirm the tank has fuel and check for any gas smell or leak
  3. Inspect the sensor harness and connector for chafing, corrosion and moisture
  4. Check the 5 V reference and ground at the sensor connector
  5. Compare the scan tool pressure reading with a mechanical gauge
  6. Test the signal wire to the ECM for opens and shorts to ground
  7. Check tank valves and lines for leaks or malfunction
  8. Clear the code and see if it returns after a test drive

Common fixes

  • Repair the wiring or replace the connector
  • Replace the alternative fuel tank pressure sensor
  • Fix the leak or faulty tank valve
  • Refuel the tank and verify system operation

Questions and answers

What does P01A0 mean?

The ECM sees a low signal in the pressure sensor circuit of alternative fuel tank A. It is more often a sensor or wiring problem than a real pressure problem.

Can I drive with P01A0?

Usually yes, briefly and with care. Have it diagnosed soon, and if you smell gas, stop and inspect the system right away.

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.