Powertrain
generic / SAE
P24E8
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.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / E8
Possible causes
- Heater control wire shorted to battery voltage high
- High-side driver stuck on medium
- Connector pins corroded - high contact resistance low
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 180–900 €
- Estimated time: 0.6–2 h
- Component: nh3 sensor heater
- Component: heater driver
- Component: sensor wiring
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012