P24E8NH3 Sensor Heater Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- With P24E8 the heater circuit of the NH3 sensor reads too high. Either the line is shorted to a supply voltage so that the heater cannot be switched off, or the driver measures overcurrent because the element has failed with low resistance. A heater stuck on can overheat and crack the ceramic, so the controller normally shuts it down and stops evaluating ammonia until the fault clears. No manufacturer documents P24E8 publicly. CARB's heavy-duty regulation treats heater current or voltage drop outside the specified limits as a malfunction. Navistar's N13 shows that faults of this heater are reported by the smart sensor itself. P24E7 is the low counterpart, P24E6 the open circuit.
- What you may notice
- Malfunction indicator lamp on
- Ammonia sensor reading switched off
- Likely causes
- LikelyHeater control line shorted to battery voltage
- PossibleHeater element failed with low resistance, causing overcurrent
- RareHeater driver in the sensor module defective
- 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: €100 – €1,400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.