P01A0

What it means

P01A0 means the control unit has seen the signal from the Alternative Fuel Tank A pressure sensor fall below its expected range, which points to a low-voltage or short-to-earth circuit fault. The alternative fuel is typically gas such as LPG or CNG, depending on the vehicle. The control unit can no longer trust the tank pressure reading, so it may restrict or stop running on that fuel.

Symptoms

• Engine warning light on
• Car will not switch to, or stays off, the alternative fuel
• Running on petrol only when it should be using the alternative fuel
• Fuel gauge or fuel level display for the alternative fuel reads wrong or zero
• Reduced range or higher petrol consumption
• Possible hesitation or rough running during fuel changeover

Possible causes

• Damaged, chafed or shorted wiring to the tank pressure sensor signal circuit (shorted to earth)likely
• Corroded, loose or water-contaminated connector at the pressure sensorlikely
• Faulty alternative fuel tank pressure sensorlikely
• Open or poor sensor supply voltage or earth, pulling the signal lowpossible
• Fault in the alternative fuel control unit or its connection to the engine control unitpossible
• Genuinely very low tank pressure, for example an empty tank or a fault in the tank valve or supplypossible
• Outdated or faulty control unit software where a known issue is documented for that modelrare

How to diagnose

1. Read all stored codes and freeze frame data, noting fuel type in use, tank pressure reading and conditions when the code set.
2. Check whether the alternative fuel tank actually contains fuel and compare the live tank pressure reading with the expected value for that system.
3. Visually inspect the sensor, its wiring and connector for damage, rubbing, heat damage, corrosion, moisture or loose pins.
4. Check for any smell of gas or signs of leaks around the tank and lines using the correct leak detection method for that fuel system, and stop if a leak is suspected.
5. With the ignition on, measure the sensor supply voltage, earth and signal voltage at the connector against the manufacturer data for that model.
6. Wiggle test the harness while watching the live pressure reading to find intermittent faults, and check the signal wire for a short to earth with the connector disconnected.
7. Check the wiring continuity back to the control unit and look for any fault codes on the alternative fuel control unit.
8. Check for applicable software updates or technical bulletins for that model if wiring and sensor test good.

How to fix

• Repair or replace damaged wiring and insulation on the signal, supply or earth circuit.
• Clean, repair or replace corroded or damaged connectors and terminals, and ensure they are dry and fully seated.
• Replace the alternative fuel tank pressure sensor if its output is out of range or fixed low despite a good supply and wiring.
• Refuel or correct any supply or valve fault if the pressure is genuinely low.
• Repair or replace the alternative fuel control unit if testing confirms it is at fault, and apply any approved software update if a known issue applies.
• Clear the code after repair and road test to confirm it does not return.

Can I keep driving?

Nearby codes

• P019FGenericAlternative Fuel Tank A Pressure Sensor Performance
• P01A1GenericAlternative Fuel Tank A Pressure Sensor Circuit High