Code Definition

P0404 — Exhaust Gas Recirculation Circuit Range/Performance

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0404

P0404 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0404 is stored, the module has detected a plausibility fault — the measured value is in the electrical range but is not consistent with expected operating behaviour.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0404 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The ECM/PCM sets this code when it detects that the EGR valve position or flow does not match the expected values during operation. This can be caused by a malfunctioning EGR valve, position sensor issues, or electrical faults in the control circuit. Incorrect EGR operation can lead to drivability issues such as rough idling, hesitation, or increased emissions.

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