OBD-II code · Powertrain (generic, extended)
P24E9 NH3 Sensor Heater Circuit Performance
The heater of the NH3 slip sensor is electrically intact, but the warm-up profile or steady-state temperature feedback does not match the ECM model. The sensor takes too long to reach operating temperature or drifts away from setpoint, so SCR closed-loop control is delayed or held off.
Is it safe to drive with P24E9?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyAged heater with increased resistance
- PossiblePoor thermal contact between heater and sensing cell
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, Sensor Element
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.