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P0A0F: Engine failed to start

In a hybrid, the system asked the petrol engine to start and it did not fire up. Lack of fuel, ignition problems or a sensor are typical causes.

Code P0A0F at a glance
CodeP0A0F
SystemEngine and transmission
GroupP0Axx, Hybrid and electric
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P0A0F means

In hybrids, the combustion engine starts and stops by itself as needed, turned over by the electric motor. If the system spins it and it does not start within the expected time, it stores this code. The car may carry on for a while on electric power, but without the engine the battery will eventually run down.

Most common causes

  • Empty or nearly empty tank (the gauge can be misleading)
  • Faulty fuel pump, relay or fuse
  • Worn spark plugs, ignition coils or faulty injectors
  • Faulty crankshaft or camshaft position sensor
  • Immobiliser not recognising the key
  • Mechanical problem, such as low compression or timing out of place

Symptoms

  • Engine warning light and hybrid system warning on
  • The combustion engine does not start when it should
  • Limited power and hybrid battery running down
  • The car may stop after a while on electric power

Can you drive with P0A0F?

With care You can move with care, but on battery alone the car will eventually stop. Head straight to a garage, or to a fuel station if the tank is low.

How to check it

First, add fuel even if the gauge shows some left. With the reader, watch whether engine rpm appears while it tries to start, and check fuel trims: no rpm signal points to the crankshaft sensor.

How to read and clear P0A0F with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0A0F with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0A0F is a generic code, so it means the same on any make, for example on BMW, Ford, Mercedes-Benz, Renault, Volkswagen, Volvo. See what Final OBD does on your car in makes and models.

What does code P0A0F mean?

In hybrids, the combustion engine starts and stops by itself as needed, turned over by the electric motor. If the system spins it and it does not start within the expected time, it stores this code. The car may carry on for a while on electric power, but without the engine the battery will eventually run down.

Can you drive with P0A0F?

You can move with care, but on battery alone the car will eventually stop. Head straight to a garage, or to a fuel station if the tank is low.

How do you clear P0A0F?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0A0F comes back.