P0406: Exhaust Gas Recirculation (EGR) (G98), Signal too High
Complete diagnostic information, symptoms, and potential causes
Manufacturer-Specific Variations
This code (P0406) 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.
Exhaust Gas Recirculation (EGR) (G98), Signal too High
Description
EGR position sensor A (G98) signal too high
Common Symptoms
- Check Engine Light with EGR position sensor signal too high
- EGR position sensor excessive signal strength issues
- Position monitoring signal limiting problems
- EGR system operation with high position signal
- Emission control monitoring system signal overload conditions
- Failed sensor tests due to high signal amplitude
Possible Causes
- Faulty EGR position sensor (G98) with excessive output
- Short circuit in sensor signal wiring
- Electrical interference affecting sensor circuit
- Sensor mounting or calibration issues causing high output
- Signal conditioning problems in sensor circuit
- Engine control module sensor input protection issues
Diagnosis Steps
- Test EGR position sensor (G98) signal amplitude
- Check for short circuits in sensor wiring
- Monitor for interference in sensor circuit
- Verify sensor mounting and calibration
- Test sensor circuit signal conditioning
- Check engine control module sensor input protection
Repair Solutions
- Replace faulty EGR position sensor (G98)
- Repair short circuits in sensor wiring
- Shield sensor circuit from interference
- Adjust sensor mounting and calibration
- Fix sensor circuit signal conditioning
- Reset EGR position monitoring system
Prevention Tips
- Regular sensor signal amplitude monitoring
- Protect sensor wiring from shorts
- Maintain proper sensor calibration
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, VAG (VW, Audi, Porsche, Skoda, Seat, Cupra), PSA (Peugeot, Citroën, DS), Mercedes-Benz, Renault / Dacia / Samsung, Ford (EDC16, EDC17, MD1, MEVD17, MSV/MSD (7X/8X/9X), MS45, DCM3.7, DCM6.x, PCR2.1, DCM3.4, SID201, SID208, SID803/803A, SID3xx (307, 310), SID3xx (301, 305, 307, 309, 310), SID202-SID206, SID209-SID211). Free: 3 removals/day.