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Emergency
FAULT CODE READING

OBD2 codes.

A code identifies a signal or system that needs to be checked, not a part you should replace.

Got an OBD2 Bluetooth adapter? Read the codes straight from your car.

1 code entry · 0 related faults

P242FParticulate filter restricted by ash (bank 1)Urgency medium

Particulate Filter Restriction Ash Accumulation Bank 1

The particulate filter burns off soot, but the ash left by the oil does not burn: it builds up over the kilometres until the filter is full.

What the car has detected

The ECU works out that the filter holds so much ash, or is so restricted, that regenerations can no longer clean it.

The car usually goes into limp mode. A badly restricted filter raises exhaust back-pressure and can damage the turbo, so drive gently and have it checked soon.

Symptoms

  • Engine or DPF warning light on
  • Loss of power or limp mode

Possible causes

  • Ash built up over high mileage
  • Wrong engine oil or oil burning
  • Damaged particulate filter
  • Software that does not match the filter fitted

Checks for the garage

  • Read the ash and soot load with the diagnostic tool
  • Check the differential pressure sensor and its pipes
  • Run a service regeneration if the garage thinks it possible

Next step

Ask for the filter’s ash and soot load to be read: it may need a professional clean or replacing.

Go to a garage soon. After replacing or cleaning the filter it must be registered in the ECU with a diagnostic tool.

Original sources · Date indicated: 2026-10-28

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