P0404: EGR circuit range or performance problem
The EGR valve is not reaching the position the ECU expects, or its signal does not add up. Usually carbon slowing it or a failing position sensor.
| Code | P0404 |
|---|---|
| System | Engine and transmission |
| Group | P04xx, Emissions control |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0404 means
The ECU commands the EGR to a position and reads where it actually is. If the difference is large or the response is slow, it stores this code. The circuit works, but the valve or its reading is not behaving as it should.
Most common causes
- Dirty EGR valve that moves sluggishly
- Carbon on the valve seat stopping it closing properly
- Poor connector contact giving intermittent readings
- Worn EGR position sensor
- Faulty EGR valve
Symptoms
- Engine warning light on
- Rough idle
- Hesitation or loss of power
- Possible limp mode
Can you drive with P0404?
With care You can drive, but the engine may run unevenly and limit power. Worth fixing soon.
Open the bonnetthe in-depth explanation
How to check it
If your reader shows commanded and actual EGR position, compare them as you rev and release the throttle: if the actual value lags or falls short, the valve is sticking or dirty.
How to read and clear P0404 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0404 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P0400 Exhaust gas recirculation (EGR) flow malfunction
- P0401 Exhaust gas recirculation (EGR) flow insufficient
- P0402 Exhaust gas recirculation (EGR) flow excessive
- P0403 EGR control circuit malfunction
- P0405 EGR sensor A circuit low
- P0406 EGR sensor A circuit high
- P0407 EGR sensor B circuit low
- P0408 EGR sensor B circuit high
- P0409 EGR sensor A circuit malfunction
- P0410 Secondary air injection system malfunction
- P0411 Secondary air injection incorrect flow detected
- P0412 Secondary air switching valve A circuit malfunction
To understand it properly
We explain how that system works, with drawings and no waffle, in our mechanics guide: EGR and particulate filter.
What does code P0404 mean?
The ECU commands the EGR to a position and reads where it actually is. If the difference is large or the response is slow, it stores this code. The circuit works, but the valve or its reading is not behaving as it should.
Can you drive with P0404?
You can drive, but the engine may run unevenly and limit power. Worth fixing soon.
How do you clear P0404?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0404 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
