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P242F: Diesel particulate filter restriction: ash accumulation

The diesel particulate filter is full of ash, a residue that does not burn off during regeneration. It usually means the filter is at the end of its life.

Code P242F at a glance
CodeP242F
SystemEngine and transmission
GroupP24xx, EGR, EVAP and particulate filter
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P242F means

The diesel particulate filter (DPF) traps soot from the exhaust and burns it off from time to time in a regeneration. Ash, which comes mainly from oil additives, does not burn and slowly builds up. The ECU estimates there is now so much that the filter can no longer work properly.

Most common causes

  • Filter at the end of its service life from normal ash build-up
  • Engine oil that is not the low-ash type the manufacturer specifies
  • Engine burning oil (turbo, piston rings or seals)
  • Ash counter not reset after the filter was replaced or cleaned
  • Pressure sensor or its pipes giving a false reading

Symptoms

  • Engine or DPF warning light on
  • Loss of power or limp mode
  • Higher fuel consumption
  • Regenerations do not clear the warning

Can you drive with P242F?

With care You can drive carefully to a garage, but do not delay: a saturated filter restricts the exhaust, saps power and can put the car into limp mode.

How to check it

On your scanner, look at the estimated ash load and the DPF differential pressure. If the filter was recently replaced or cleaned, ask the garage whether the values were reset with diagnostic equipment.

How to read and clear P242F 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 P242F 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

P242F is a generic code, so it means the same on any make, for example on BMW, Ford, Mazda, Mercedes-Benz, Peugeot, Volkswagen. See what Final OBD does on your car in makes and models.

What does code P242F mean?

The diesel particulate filter (DPF) traps soot from the exhaust and burns it off from time to time in a regeneration. Ash, which comes mainly from oil additives, does not burn and slowly builds up. The ECU estimates there is now so much that the filter can no longer work properly.

Can you drive with P242F?

You can drive carefully to a garage, but do not delay: a saturated filter restricts the exhaust, saps power and can put the car into limp mode.

How do you clear P242F?

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, P242F comes back.