Code
P1401
DAEWOO
P — Powertrain
EGR TEMP. SENSOR
Views:
UK: 3
EN: 10
RU: 5
AI status
Completed
Completed
100%
Causes
- Faulty EGR temperature (EGR temp) sensor (thermistor)
- Open, shorted, or intermittent wiring between sensor and ECM
- Corroded, loose or contaminated connector/pins at sensor or ECM
- Soot/contamination or physical damage to sensor from exhaust gases
- Poor ground or missing reference voltage to the sensor
- Exhaust leak or blocked EGR passages causing abnormal sensor readings
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
- Possible reduced engine performance or limp mode depending on strategy
- Failed emissions test or elevated tailpipe emissions
- Rough idle or hesitation under some conditions
- Possible reduced EGR duty or altered engine fueling (stability/knock risk)
What to check
- Read DTCs and freeze frame data with a scan tool; record pending/confirmed status
- Monitor live data: EGR temperature value while cold, during warm‑up, and under load
- Inspect EGR temp sensor connector and wiring for corrosion, heat damage, chafing or disconnection
- Backprobe sensor connector and verify reference voltage and ground at key ON and running conditions
- Wiggle harness while monitoring live data to reproduce intermittent faults
- Visually inspect EGR valve, cooler and passages for heavy soot/contamination or obvious exhaust leaks
Signal parameters
- Typical EGR temperature sensor: NTC thermistor type — resistance falls as temperature rises
- Resistance examples (approximate, vehicle-specific): ~2k–5kΩ at ~20°C (68°F);
- Voltage output (if measured as a sensor voltage): commonly within ~0.5–4.5 V depending on temperature and circuit design
- Reference supply to sensor commonly 5 V from ECM; ground continuity should be near 0 Ω to chassis ground (verify on vehicle)
- No open circuit — expected continuity from sensor connector to ECM pin; typical wiring resistance should be low (ohms)
Diagnostic algorithm
- Verify DTC: Use a scan tool, read P1401 and any related codes. Note freeze frame and clear codes to see if they return.
- Visual inspection: Inspect sensor, connector, and wiring harness for damage, corrosion, soot, or heat-related deterioration. Repair any visible issues.
- Monitor live data: With scan tool, observe EGR temp reading at key ON, engine start, idle and under load. Look for unrealistic values (stuck high/low) or rapid jumps/intermittency.
- Check reference/ground: Backprobe the sensor connector. With key ON, confirm the ECM reference voltage (often ~5 V) and a good ground. If reference/ground missing, trace wiring to ECM.
- Measure sensor resistance: Remove connector and measure sensor resistance at ambient and after warming (if safe). Compare to OEM spec. If out of range, replace sensor.
- Continuity/short tests: With battery disconnected, check continuity from sensor pins to ECM pins and check for shorts to ground or to other circuits.
- Inspect EGR system: Check for clogged EGR passages or cooler soot that could affect sensor readings; inspect for exhaust leaks upstream of sensor.
- Repair/replace: Replace the EGR temp sensor or repair wiring/connectors as indicated. Use OEM or equivalent parts rated for exhaust environment.
- Verify repair: Clear codes, test drive under varied conditions and re-scan to confirm P1401 does not return. Record live EGR temperature behavior to ensure proper function.
Likely causes
- Failed EGR temperature sensor (thermistor)
- Wiring harness connector corrosion or broken wire to sensor
- Sensor contaminated with soot or damaged by heat/pressure
Fault status
Status
EGR temperature sensor circuit malfunction — signal out of range, intermittency, or no signal detected.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email