NH3 Sensor Heater Circuit High
The heater control circuit of the NH3 slip sensor reads above the expected voltage range. Typically a short to battery voltage or a heater driver stuck high — duty-cycle control is lost, the heater either runs continuously or not at all, and the sensor element risks overheating before the ECM disables it.
Affected components
- Nh3 sensor heater
- Heater driver
- Sensor wiring
Common causes
- High likelihood: Heater control wire shorted to battery voltage
- Medium likelihood: High-side driver stuck on
- Low likelihood: Connector pins corroded - high contact resistance
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.