OBD-II code · Powertrain (generic, extended)
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.
Is it safe to drive with P24E6?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyBurnt-out heater winding inside the sensor
- PossibleBroken wire or unplugged connector
- Less likelyFailed heater driver stage in the dosing module
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.6–2 h
- Emissions test
- Likely to fail
- Parts involved
- Nh3 Sensor Heater, Heater Driver, Sensor Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.