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TuningBot DTC Database · v4.37.15

P0400 Exhaust Gas Recirculation Flow Malfunction

Generic (OBD-II) interpretation + 1 manufacturer-specific in the TuningBot DTC database.

P · PowertrainEmissionsOBD2
Brand pages:Ford

Generic (OBD-II) interpretation

P0400
Exhaust Gas Recirculation Flow Malfunction Generic · emissions Data confidence 90%

The control module detected improper operation of the Exhaust Gas Recirculation Flow.

Symptoms

  • MIL illuminated
  • Possible reduced engine performance
  • Possible rough idle or hesitation

Possible causes

  • Hose leak/blockage
  • basic setting not carried out (if applicable)
  • wiring
  • EGR valve
  • EGR solenoid
  • ECM

Recommended checks

  • Read freeze frame data and full module scan
  • Check battery voltage and sensor supply
  • Inspect EGR wiring and connectors
  • Compare commanded vs actual EGR position/flow with live data
  • Inspect EGR valve and passages for carbon build-up
  • Check related vacuum lines where fitted

Manufacturer-specific interpretations

Ford

1 interpretation
P0400:9C
Insufficient EGR Flow Ford · emissions Data confidence 94%

Ford documents P0400:9C for its 2024-2025 gasoline-engine OBD monitor strategy as insufficient egr flow. This three-byte interpretation is application-specific and identifies the detected monitor condition rather than a confirmed failed component.

Recommended checks

  • Perform a full module scan
  • Review freeze-frame and occurrence data
  • Compare commanded and measured values
  • Check applicable OEM service information
Applies to Ford gasoline-engine OBD applications|2024-2025 model years

Related and nearby codes

How to read P0400

P

Powertrain: engine, transmission and driveline systems.

0

Generic SAE-standard code: same meaning on every make.

400

Specific fault index within the subsystem.

Frequently asked questions about P0400

What does P0400 mean?

Exhaust Gas Recirculation Flow Malfunction. The control module detected improper operation of the Exhaust Gas Recirculation Flow.

Is P0400 generic or manufacturer-specific?

P0400 exists both as a generic OBD-II code (same meaning on every make) and with 1 manufacturer-specific interpretation(s): Ford. Always read it in the context of your vehicle.

Can TuningBot remove P0400 at file level?

If the fault logic lives in the ECU calibration, yes: our DTC Removal file service disables the specific fault entry. Checksum correction is not included: it is a separate, optional service. Not sure whether your case qualifies? Request a free assessment and our engineers will check your ECU file.

Other file services

ECU tuningStage 1 dyno results for Ford engines See the results →

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