P0403 Code: EGR Control Circuit — Causes & Fix
P0403 means an electrical fault in the exhaust gas recirculation (EGR) control circuit — the ECM cannot properly command the EGR valve.
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $40 – $500
- Time to fix
- 30 minutes – 2 hours
What it means
Causes include a failed EGR valve/solenoid, a connector fault, or damaged wiring. P0403 is a generic OBD-II powertrain code defined in the SAE J2012 standard, so it applies to virtually any 1996-or-newer petrol car or light truck regardless of make. Fix the underlying fault, then clear the code with an OBD-II scan tool — it will return if the problem isn't resolved.
Symptoms
- Check engine light on
- Possible pinging or rough idle
- May fail emissions
How to fix it
- 1
Inspect the EGR valve and wiring
1. Locate the EGR valve/solenoid. 2. Reseat the connector and check the wiring.
- 2
Test and replace
1. Check the EGR solenoid operation. 2. Replace if faulty, then clear the code.
Frequently asked questions
What does the EGR valve do?
It recirculates a little exhaust back into the intake to lower combustion temperature and NOx emissions. P0403 is an electrical fault in its control.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.