P24E9NH3 Sensor Heater Circuit Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P24E9 is not about a broken wire but about how the heater works: the circuit is intact, yet the NH3 probe does not reach or hold its operating temperature in the expected time, or its temperature control swings. Deutz lists P24E9 for its MD1 engine controller as SPN 4382 with FMI 2, meaning erratic or incorrect heater data. Navistar handles the similar case on the 2013 N13 as SPN 5848 FMI 10, an abnormal rate of change, where the probe or its module are the named suspects. Aged heater elements, cold exhaust from long idling and moisture on the ceramic play a role. CARB's heavy-duty rule requires heater performance checks. Electrical heater faults are P24E6 to P24E8.
- What you may notice
- Check engine light, often together with an NH3 sensor performance code
- Ammonia reading available late or unstable
- Likely causes
- LikelyAged heater element no longer delivering full power
- PossibleCondensate on the ceramic cooling it or causing thermal shock
- RareLow supply voltage limiting heater power
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €250 – €1,400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.