P24ECNH3 Sensor Supply Voltage Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P24EC is stored when the feed voltage measured at the NH3 sensor module exceeds its upper limit. Overvoltage can damage the heater driver and the electronics, so the module may switch off heating and measurement to protect itself. Likely triggers are a charging system that regulates too high, jump-starting with a higher-voltage source, or a short from a higher feed onto the sensor supply line. No manufacturer publishes P24EC; for the component itself, Navistar's N13 bulletin describes the sensor as a probe paired with its own electronics module on the J1939 link. CARB's heavy-duty rule requires out-of-range detection on such circuits. Check the charging voltage first. P24EB is the low fault, P24EA the general one.
- What you may notice
- Check engine light on
- Other modules may also report high system voltage
- Likely causes
- LikelyAlternator regulator charging too high
- PossibleOvervoltage from jump-starting or a booster charger
- RareSensor supply line shorted to another higher feed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.