P0402
EGR Flow Excessive
medium
i Description
The EGR system is flowing too much exhaust gas back into the intake. Excessive EGR dilutes the air/fuel mixture too much, causing rough idle and stalling.
? Common Causes
- EGR valve stuck open
- Leaking EGR vacuum line
- Faulty EGR solenoid (stuck open)
- DPFE sensor fault
! Symptoms
- Check engine light
- Rough idle
- Engine stalling
- Hesitation at low RPM
- Possible no-start when engine is warm
# Diagnostic Steps
- Disconnect EGR vacuum line — if idle improves, valve is stuck open
- Inspect EGR valve for carbon preventing full closure
- Test EGR vacuum solenoid
- Check DPFE sensor readings
⚙ Typical Fix
Clean or replace the EGR valve. Fix the sticking issue.
Parts Needed
EGR valve, EGR gasket
Estimated Cost
$100-$400
↔ Related Codes
Q Frequently Asked Questions
The car may stall at idle, which is annoying but not dangerous. Drive with caution and get it fixed promptly.
☞ Learn More
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