NOx Sensor Heater Circuit (Bank 1)
What does P2205 mean?
The P2205 code means the vehicle's onboard diagnostic system has detected: NOx Sensor Heater Circuit (Bank 1). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Slow sensor warm-up in cold weather
- Failed emissions test
- Temporary limp mode on cold start
- Elevated cold-start emissions
Probable Causes (Ranked by Likelihood)
- Failed NOx sensor heater element Very High
- Open or short in the heater circuit wiring High
- Blown fuse for the NOx sensor heater circuit Moderate
- Poor ground connection for the heater circuit Moderate
- ECM heater driver circuit failure Low
Step-by-Step Diagnostic Procedure
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Check the NOx sensor heater fuse in the fuse box
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Measure heater circuit resistance at the sensor connector -- compare to spec
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Verify power and ground are present at the sensor connector with the key on
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Inspect wiring between the ECM and NOx sensor for opens or shorts
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Replace the NOx sensor if the heater element has failed internally
Frequently Asked Questions
Why does the NOx sensor need a heater?
NOx sensors must reach a high operating temperature (typically over 600 degrees F) to function accurately. The heater element brings the sensor up to temperature quickly after a cold start.
Can a blown fuse cause P2205?
Yes, always check the fuse first as it is the simplest and cheapest potential fix. A blown fuse cuts power to the heater circuit entirely.
Will P2205 cause the truck to go into limp mode?
Some vehicles will temporarily limit power during cold starts if the NOx sensor heater is not working, since the SCR system cannot operate properly until the sensor reaches operating temperature.