What does code P0404 mean?

P0404 — EGR valve control range out of spec — valve moves, but position doesn't match commanded value. Common past 100K km on diesels. Belongs to the powertrain.emission system. Severity: warning.

What are the common causes of P0404?

Carbon-fouled EGR stem — moves in jerks; Worn EGR position sensor; Damaged wiring or bad connector contact; Weak vacuum supply (vacuum-actuated EGR); Failed electric motor (electric EGR)

Can I drive with code P0404?

Limited: reaching the nearest workshop is fine, but avoid long trips. May progress into a more serious fault.

How do I diagnose P0404?

Read the code and freeze-frame with a scanner, check related-system errors, inspect the components listed (wiring, connectors, sensors). See the "How to diagnose" section above for the full step-by-step.

How do I clear code P0404?

The code can be cleared via an OBD-II scanner (e.g. ELM327 + the Car Diagnostics app): plug the adapter into the OBD port, go to Errors → Clear. If the underlying cause isn't fixed, the code will return within a few drive cycles.

OBD-II Code P0404 — Car Diagnostics Platform

What it means

Common causes

Carbon-fouled EGR stem — moves in jerks
Worn EGR position sensor
Damaged wiring or bad connector contact
Weak vacuum supply (vacuum-actuated EGR)
Failed electric motor (electric EGR)
Clogged EGR cooler — mechanical resistance
Calibration errors after valve replacement without adaptation

How to diagnose

01
Read all stored and pending codes with an OBD-II adapter — get the full picture, not just the one code.
02
Capture freeze-frame data (RPM, coolant temperature, engine load) at the exact moment the code triggered.
03
Inspect the named subsystem with our app's AI explanation — get vehicle-specific causes for your make, model and year.

Decode P0404 on your actual car

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