Code
P1406
GWM
P — Powertrain
- Exhaust Gas Recirculation (EGR) Sensor Adjustment
Views:
UK: 19
EN: 29
RU: 13
AI status
Completed
Completed
100%
Causes
- EGR position sensor out of calibration or misaligned after service or replacement
- Faulty EGR valve or position sensor
- Wiring harness damage, short or poor connector contact to EGR sensor/solenoid
- Contaminated, stuck or mechanically jammed EGR valve or passages
- Incorrect or incomplete adaptation/calibration procedure not performed after repair
- PCM/ECU software or calibration mismatch
Symptoms
- Check Engine Light (MIL) illuminated with P1406 stored
- Rough idle, hesitation or surge at low load
- Reduced engine performance or drivability issues
- Increased NOx emissions; possible failed emissions test
- Unusual exhaust odors or black smoke under some conditions
What to check
- Read and record freeze-frame and related codes; check for other EGR-related DTCs
- Inspect EGR valve, sensor and linkage for carbon buildup, binding or obvious damage
- Visual and wiggle test of connectors and wiring for looseness, corrosion or chafing
- Use scan tool to view live data: commanded EGR position vs actual EGR position/sensor voltage
- Confirm vehicle service history — recent EGR or intake service or sensor replacement
- Check for technical service bulletins (TSBs) or calibration updates from GWM
Signal parameters
- EGR position sensor reference: typically 5 V supply (check service manual for exact value)
- EGR sensor output voltage (typical): approximately 0.5 V at closed/low position to ~4.5 V at full open (manufacturer-specific)
- EGR sensor continuity/resistance: refer to service manual; many potentiometer sensors show variable resistance across travel
- EGR solenoid coil resistance (if applicable): commonly 15–50 ohms (verify with spec sheet)
- Compare commanded EGR % vs measured EGR position (%) using OEM scan tool; deviation beyond manufacturer tolerance triggers code
Diagnostic algorithm
- Retrieve all related DTCs and freeze-frame data. Note operating conditions when P1406 set.
- Visually inspect EGR valve, sensor, wiring harness and connectors. Repair any damaged wiring or corroded terminals.
- With a scan tool, monitor commanded EGR position and actual EGR sensor feedback while operating engine at idle and during commanded steps. Note discrepancies.
- Manually actuate the EGR valve (vacuum or electric via actuator) and observe sensor output/valve movement. Check for binding or excessive carbon build-up. Clean EGR passages if necessary.
- Measure sensor supply, ground and signal voltage at harness back-probe. Compare to signal_params and service manual values.
- If sensor signal is out of range but electrically healthy, perform EGR sensor/valve adjustment or calibration using OEM scan tool following GWM procedure.
- If sensor/actuator fails electrical tests or calibration cannot correct the discrepancy, replace the faulty component (sensor, valve or solenoid).
- After repair or replacement, perform required relearn/adaptation/calibration procedure per service manual, clear codes and perform a road/test cycle to confirm code does not return.
- If code returns despite correct hardware and calibration, verify PCM software level and apply updates or reflash as recommended by GWM.
Likely causes
- EGR valve installed in wrong orientation or sensor indexing incorrect after reassembly
- EGR position sensor potentiometer/encoder worn or failed
- Connector corrosion or terminal damage at sensor/valve
- Carbon build-up preventing EGR valve from reaching intended position
- EGR solenoid not actuating (electrical or vacuum supply fault)
- PCM requiring relearn or software update
Fault status
Status
EGR sensor/position requires adjustment or calibration — sensor feedback out of expected range. Inspect EGR system, wiring and perform OEM calibration.
Repair difficulty: Medium
Diagnostic time: 0.5-3 hours
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