P0402 — Exhaust Gas Recirculation Flow Insufficient Detected
Can drive — fix at your convenience.
What P0402 means
This code means the engine is detecting less exhaust gas recirculation (EGR) flow than it should, often because the EGR valve is stuck closed or the passages are clogged with carbon. Common fixes include cleaning carbon from the EGR valve and passages, or replacing a faulty EGR valve. It's an emissions-related code and is usually a straightforward repair.
Common symptoms
- Check engine light is on
- Light engine knock or pinging under load
- Slightly rough idle
- Reduced fuel economy
- Failed emissions or smog test
Common causes
- EGR valve stuck closed
- Carbon buildup clogging the EGR passages
- Faulty EGR valve or solenoid
- Restricted or blocked EGR tube
- Faulty EGR position or flow sensor
Typical repair cost
$150 – $500
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0402 code?
Yes, you can usually drive normally for a while since this is an emissions issue. You may notice light pinging under load or a slightly rough idle. Have it repaired within a week or two to protect fuel economy and pass emissions testing.
How much does it cost to fix a P0402 code?
Repairs typically run $150 to $500. Cleaning the EGR valve and passages is the cheaper option, while a full EGR valve replacement with labor reaches the higher end.
Is a P0402 code serious?
It's a low-severity, emissions-related code, so it's not an immediate danger. However, the light pinging can stress the engine and it will fail a smog check, so it's worth fixing soon.
What causes insufficient EGR flow in P0402?
Most often the EGR valve is stuck closed or the passages are clogged with carbon, so not enough exhaust reaches the intake. A faulty valve, a blocked EGR tube, or a bad flow sensor can also trigger it.