Exhaust Gas Recirculation Temperature Sensor Circuit Open (Generic)
The P4040 code means the vehicle's onboard diagnostic system has detected: Exhaust Gas Recirculation Temperature Sensor Circuit Open (Generic). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $80 - $300 (parts and labor)
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Common Symptoms
- Check Engine Light on
- EGR system operation impaired
- Increased NOx emissions
- Rough idle especially when warm
- Failed emissions test
Probable Causes (Ranked by Likelihood)
- Open circuit in EGR temperature sensor wiring Very High
- Failed EGR temperature sensor High
- Damaged connector from heat exposure Moderate
- PCM input circuit failure Low
Step-by-Step Diagnostic Procedure
-
Check EGR temperature sensor resistance
-
Inspect wiring from sensor to PCM for breaks
-
Verify connector integrity at EGR system
-
Test PCM input for EGR temperature signal
Frequently Asked Questions
What does the EGR temperature sensor do?
It monitors the temperature of exhaust gases being recirculated back into the intake to reduce NOx emissions.
Can I drive with P4040?
You can drive short distances. The EGR system will be limited or disabled, which increases NOx emissions.
Is P4040 related to the EGR valve?
No, P4040 is specifically about the temperature sensor circuit.
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