Complete diagnostic information for error code P0402
Manufacturer-Specific Variations
This code (P0402) may have different meanings or additional parameters depending on your vehicle's make, model, and year. Always verify with your vehicle's service manual or a qualified technician before attempting repairs.
P0402
Powertrain CodeExhaust Gas Recirculation (EGR), Excessive Flow
Description
Exhaust gas recirculation excessive flow
Common Symptoms
- Check Engine Light with EGR excessive flow detected
- Rough idle and unstable engine operation
- Poor acceleration and hesitation
- Engine stalling or stumbling at idle
- Excessive exhaust gas recirculation affecting combustion
- Reduced engine power and performance
Possible Causes
- EGR valve stuck open
- Faulty EGR valve position sensor
- Vacuum control problems causing valve to stay open
- Carbon buildup preventing proper valve closure
- EGR valve mechanical failure
- Control circuit issues keeping EGR valve open
Diagnosis Steps
- Test EGR valve for sticking open condition
- Check EGR valve position sensor readings
- Verify vacuum control system operation
- Inspect for carbon buildup affecting valve closure
- Test EGR control circuit operation
- Perform EGR flow rate measurement
Repair Solutions
- Replace stuck open EGR valve
- Repair or replace faulty position sensor
- Fix vacuum control system issues
- Clean carbon deposits from EGR valve
- Address mechanical EGR valve failures
- Repair EGR control circuit problems
Prevention Tips
- Regular EGR system maintenance
- Monitor engine idle quality
- Address rough idle issues promptly
Working with ECU firmware? Remove DTCs directly from firmware files
Our free Firmware DTC Remover detects and removes hardcoded fault codes directly from ECU firmware files — no software needed. Supports BMW/MINI (EDC16, EDC17, MEVD17) and VAG Group (EDC17). Free: 3 removals/day.