P0403: EGR control circuit malfunction
The ECU has detected an electrical problem in the circuit that drives the EGR valve. It is usually the connector, wiring or the valve itself.
| Code | P0403 |
|---|---|
| System | Engine and transmission |
| Group | P04xx, Emissions control |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0403 means
The ECU operates the EGR valve (or the solenoid that moves it) with an electrical signal. When checking that circuit it has found something wrong, such as a broken wire, a short or a damaged coil. The fault here is electrical, not carbon build up.
Most common causes
- Loose, corroded or bent pins on the EGR valve connector
- Broken or chafed wiring
- EGR valve or solenoid with a failed internal coil
- Fuse or power supply to the circuit
- ECU fault (rare)
Symptoms
- Engine warning light on
- Rough idle or hesitation
- Loss of power or limp mode
- Sometimes no symptoms
Can you drive with P0403?
With care You can usually drive, but without EGR control the engine may run worse or limit power. Have it checked soon.
Open the bonnetthe in-depth explanation
How to check it
Look at the EGR valve connector: unplug it with the engine off, check for green corrosion or bent pins and plug it back in. If the code returns, the garage should measure the coil resistance.
How to read and clear P0403 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 P0403 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
- P0404 EGR circuit range or performance problem
- 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
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 P0403 mean?
The ECU operates the EGR valve (or the solenoid that moves it) with an electrical signal. When checking that circuit it has found something wrong, such as a broken wire, a short or a damaged coil. The fault here is electrical, not carbon build up.
Can you drive with P0403?
You can usually drive, but without EGR control the engine may run worse or limit power. Have it checked soon.
How do you clear P0403?
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, P0403 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.
