OBD-II code · Powertrain (generic, extended)
P24E5 NH3 Sensor Circuit Intermittent/Erratic
The ammonia (NH3) slip sensor downstream of the SCR catalyst delivers an intermittent or erratic signal. The ECM expects a smooth voltage proportional to ammonia concentration in the tailpipe — sudden jumps, dropouts or noise mean the wiring, connector or sensing element is failing. Used to close-loop the AdBlue/DEF dosing strategy.
Is it safe to drive with P24E5?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyCorroded or loose sensor connector
- PossibleChafed or vibrating harness near the exhaust
- PossibleAged ceramic sensor element drifting under heat cycles
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, Sensor Wiring, Sensor Connector
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.