Exhaust Gas Recirculation Temperature Sensor Circuit High (Generic)
The P4042 code means the vehicle's onboard diagnostic system has detected: Exhaust Gas Recirculation Temperature Sensor Circuit High (Generic). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $80 - $300 (parts and labor)
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Common Symptoms
- Check Engine Light on
- EGR flow restricted by PCM
- Increased NOx emissions
- Higher combustion temperatures
- Possible engine knock
Probable Causes (Ranked by Likelihood)
- Short to voltage in EGR temp sensor circuit Very High
- EGR temperature sensor internal failure High
- Wiring damage near EGR system Moderate
- Reference voltage circuit issue Low
Step-by-Step Diagnostic Procedure
-
Check sensor signal voltage
-
Disconnect sensor and check for stray voltage on signal wire
-
Inspect wiring for heat damage near EGR components
-
Verify reference voltage circuit
Frequently Asked Questions
Can high EGR temp cause engine knock?
If the PCM restricts EGR flow due to a false high reading, combustion temperatures increase, which can cause knock under heavy load.
Can I drive with P4042?
You can drive short distances. Avoid towing or heavy acceleration until repaired.
What causes wiring damage near the EGR?
The EGR system operates at very high temperatures. Wiring routed near EGR components can degrade over time.
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