P0402Severity: Low
P0402 – EGR Excessive Flow
Exhaust gas recirculation (EGR) flow is higher than expected.
What it means
The EGR system routes some exhaust gas back into the intake to cut emissions. If flow is too high, idle gets rough; usually a stuck-open valve or control issue.
Symptoms
- Rough idle/stalling
- Loss of power
- Check-engine light
Common causes
- Stuck-open EGR valve
- Control/wiring issue
- Clogged EGR passages
- Vacuum issue
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Frequently asked questions
What does trouble code P0402 mean?
P0402 – EGR Excessive Flow. The EGR system routes some exhaust gas back into the intake to cut emissions. If flow is too high, idle gets rough; usually a stuck-open valve or control issue.
Can I drive with a P0402 code?
It's usually not urgent, but finding and fixing the cause matters for emissions and fuel economy.