Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 1 Low (Generic)
The P4001 code means the vehicle's onboard diagnostic system has detected: Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 1 Low (Generic). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $80 - $350 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Inaccurate exhaust temperature reading
- DPF regeneration issues
- Reduced engine power
Probable Causes (Ranked by Likelihood)
- Short to ground in EGT sensor wiring Very High
- Failed EGT sensor reading low High
- Water intrusion in sensor connector Moderate
- Damaged wiring harness near exhaust Low
Step-by-Step Diagnostic Procedure
-
Measure EGT sensor resistance at various temperatures
-
Check wiring for shorts to ground
-
Inspect connector for moisture or corrosion
-
Verify PCM is receiving correct voltage signal
Frequently Asked Questions
Is P4001 dangerous?
It is moderate severity. You can drive short distances but DPF regeneration may not work properly, which can lead to a clogged filter over time.
What causes P4001?
Most commonly a short to ground in the EGT sensor wiring, often caused by heat damage to the harness near the exhaust system.
Can I fix P4001 myself?
The repair requires working under the vehicle near hot exhaust components. If you are comfortable with wiring repair, it is possible but generally recommended for a professional.
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