P0402 Code: EGR Excessive Flow — Causes & Fix
P0402 means exhaust gas recirculation (EGR) flow is excessive — too much exhaust is being recirculated.
- 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 stuck-open EGR valve, a leaking EGR gasket, or a control fault. P0402 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
- Rough idle or stalling
- Hesitation at low speed
How to fix it
- 1
Check the EGR valve
1. Confirm the valve is not stuck open and seats fully. 2. Clean or replace it.
- 2
Inspect gaskets/control
1. Check the EGR gasket and control solenoid. 2. Repair, then clear the code.
Frequently asked questions
Why does my engine stall at idle with P0402?
Too much recirculated exhaust at idle dilutes the mixture and can cause a rough or stalling idle. A stuck-open EGR valve is the usual cause.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.