Powertrain
generic / SAE
P24E6
NH3 Sensor Heater Circuit/Open
The heater inside the ammonia (NH3) slip sensor warms the sensing cell to operating temperature so it can read tailpipe ammonia. The ECM detects an open in the heater control circuit — no current flows when the heater should be active, so the sensor never reaches its working point and SCR closed-loop control is suspended.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / E6
Possible causes
- Burnt-out heater winding inside the sensor high
- Broken wire or unplugged connector medium
- Failed heater driver stage in the dosing module low
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 200–950 €
- 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