EGR Codes P0400, P0401 and P0403: Meaning, Causes and DTC Off

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What do the EGR codes mean?

  • P0400: Exhaust Gas Recirculation (EGR) flow malfunction.
  • P0401: EGR flow insufficient detected.
  • P0403: EGR control circuit malfunction.

Common causes

  • Carbon build-up in the EGR valve, cooler or passages.
  • A stuck or worn EGR valve.
  • Wiring or connector problems on the valve or its position sensor.
  • A faulty EGR position or flow sensor.

Is the valve dead?

Not always. Carbon build-up is the most common reason, and cleaning the valve and passages can solve it. Check the wiring and live data before replacing parts.

EGR DTC off for Denso ECU files

For competition and off-road vehicles, upload your readout, select the right generation and enter the EGR codes you want disabled in the DTC list. Start from the Denso Gen 4 guide for the full list of what we need, and use the flashing checklist before you write the file.

⚠️ Modified files are intended exclusively for competition and off-road vehicles. Using them on public roads may violate local regulations and is the user's responsibility. See our Terms & Conditions.

Frequently asked questions

Does DTC off fix a stuck EGR valve?

No. It only disables the selected codes in the ECU file. A mechanical problem stays a mechanical problem.

Which ECU generations do you support?

Gen 1 to Gen 4. Select the right generation when you upload the file.

Can I use the modified file on a road vehicle?

No. Files from this service are intended exclusively for competition and off-road vehicles. Using modified ECU files on public roads may violate local regulations and is the user's responsibility.

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