P0404
PPowertrainEGR Circuit Range/Performance
What does this code mean?
Severity : MediumP0404 indicates an EGR circuit range or performance problem. The electrical circuit works, but the actual valve position does not match what the ECU commands, or the valve reacts too slowly. It often points to a carbon-fouled valve that binds or a drifting position sensor.
Symptoms
- Check engine light on.
- Unstable idle.
- Poor response or hesitation.
- Black smoke on diesel engines.
- Possible limp mode on some vehicles.
Possible causes
- Carbon-fouled EGR valve that moves poorly.
- Faulty or misadjusted EGR valve position sensor.
- Poor connector contact or high resistance in the wiring.
- Worn EGR valve motor.
- Vacuum supply problem on vacuum-operated valves.
Diagnosis and repair
- Check the EGR valve connector and wiring.
- Compare commanded and actual valve position in live data.
- Clean the valve and check that it moves freely through its full travel.
- Replace the valve if the deviation remains after cleaning.
- Run the valve adaptation if the manufacturer requires it, then clear the code.
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Code
P0404
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012