OBD-II code · Powertrain (generic, extended)
P24EA NH3 Sensor Supply Voltage Circuit
The supply rail that powers the NH3 slip sensor electronics (typically 5 V or 12 V from the dosing/SCR module) is out of tolerance. Without a stable supply the sensor cannot deliver a valid ammonia reading, and the ECM disables the closed-loop SCR strategy.
Is it safe to drive with P24EA?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen or shorted supply wire
- PossibleFailing supply rail inside the dosing module
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- Parts involved
- Nh3 Sensor, Supply Wiring, Dosing Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.