NOx Sensor Heater Circuit High (Bank 1)
The P2207 code means the vehicle's onboard diagnostic system has detected: NOx Sensor Heater Circuit High (Bank 1). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- hard
- Estimated cost
- $250 - $800 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Possible burnt wiring smell
- Failed emissions test
- SCR system warning
- Potential limp mode
Probable Causes (Ranked by Likelihood)
- Short to voltage in the heater circuit wiring Very High
- Internally shorted NOx sensor heater element High
- Water intrusion causing a short in the connector Moderate
- Melted wiring from proximity to exhaust components Moderate
- ECM heater driver outputting excessive current Low
Step-by-Step Diagnostic Procedure
-
Measure heater circuit current draw -- compare to manufacturer spec
-
Inspect wiring for shorts to power, especially near exhaust heat sources
-
Check the sensor connector for water intrusion or melted pins
-
Measure heater element resistance -- a very low reading indicates internal short
-
Replace the NOx sensor if heater element is shorted
Frequently Asked Questions
What causes the heater circuit to read high?
A high reading indicates excessive current in the heater circuit, usually from a short to voltage in the wiring or an internally shorted heater element that has lower-than-normal resistance.
Can a high heater circuit damage other components?
Yes, excessive current can blow fuses, damage the ECM heater driver circuit, or cause wiring to overheat, so this code should be addressed promptly.
How do I prevent NOx sensor heater failures?
Ensure the wiring harness heat shielding is intact, keep connectors clean and sealed, and address any exhaust leaks that could expose wiring to excessive heat.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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