Code
P1406
HUMMER
P — Powertrain
EGR Valve Pintle Position Circuit
AI status
Completed
Completed
100%
Causes
- Open or short in EGR pintle position sensor wiring or connector
- Corroded, bent or disconnected connector pins at the sensor
- Failed EGR valve position sensor or integrated pintle position sender
- Sticking or mechanically binding EGR pintle/valve
- Poor ground or lost reference voltage (5V) to the sensor
- PCM fault (rare) or intermittent wiring fault
Symptoms
- Check Engine Light (MIL) illuminated
- Reduced engine performance or rough idle
- Possible increased NOx emissions or failed emissions test
- Poor throttle response or hesitation under load
- Engine surging during certain load conditions (if EGR stuck)
What to check
- Read and record freeze frame and all stored codes with a scan tool; note live EGR pintle position value
- Visual inspection of EGR valve, sensor connector and wiring for damage, corrosion or contamination
- Backprobe sensor connector and monitor pintle position voltage while commanding EGR with a scan tool
- Confirm sensor reference voltage (typically 5 V) and good ground at the connector with ignition ON
- Wiggle wiring harness while monitoring live data to reveal intermittent faults
- Check for related codes (EGR flow/position, PCM power/ground issues)
Signal parameters
- Sensor type: position potentiometer or hall-effect position sensor (analog voltage feedback)
- Expected reference voltage: ~5 V (key ON) to the sensor reference pin
- Typical feedback voltage range: about 0.2–4.8 V depending on pintle position (closed ≈ low voltage, open ≈ high voltage) — values vary by model; consult service manual
- Signal behavior: smooth, proportional voltage change as EGR pintle moves; no sudden jumps to battery or ground
- Noisy, stuck at a fixed voltage, or open-circuit voltage (~0 V) indicates a fault
Diagnostic algorithm
- Retrieve freeze frame and all related codes. Note engine conditions when fault set.
- Perform a thorough visual inspection of the EGR valve, sensor harness and connectors. Repair any obvious damage.
- With a scan tool, monitor the EGR pintle position PID. Command the EGR open/close and observe whether the feedback voltage changes smoothly.
- If PID does not change, backprobe the sensor connector. Verify sensor reference voltage (~5 V) with ignition ON, check sensor ground for continuity to chassis ground.
- Measure the sensor output voltage at rest and while commanding movement. Compare to expected range from service information; look for shorts to 0 V or battery voltage.
- If reference and ground are correct but the output is invalid or does not vary, disconnect connector and check wiring continuity to the PCM and for shorts to battery/ground.
- Repair any wiring or connector faults. After repairs, clear codes and re-test for proper operation and absence of code.
- If wiring and connectors check good and the sensor output is still out of range, replace the EGR valve/position sensor assembly and retest.
- Replace the PCM only if the sensor, wiring and power/ground have been thoroughly verified and the fault points to the module.
Likely causes
- Wiring harness damage near the engine (heat, chafe, rodent)
- Water intrusion/corrosion at the sensor connector
- Failed EGR valve assembly with internal sensor fault
- Carboned or seized pintle that prevents expected position change
- Faulty sensor reference (missing 5V) or ground
Fault status
Status
EGR valve pintle position circuit fault detected — position sensor signal out of range, open, shorted or intermittent.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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Repair manuals
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138
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