OBD-II code · Powertrain (generic, extended)
P24EC NH3 Sensor Supply Voltage Circuit High
The NH3 slip sensor supply voltage rises above the upper limit. Either the supply is shorted to battery voltage or an internal regulator in the dosing module has failed open. The sensor electronics may be damaged if the condition persists, so the ECM disables the input.
Is it safe to drive with P24EC?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySupply line shorted to battery voltage
- PossibleFailed voltage regulator in the dosing module
- Less likelyConnector pins corroded - high contact resistance
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.