P24E3 code meaning
NH3 Sensor Circuit Low
Powertrain system Generic code P24xx codes Check engine light
What P24E3 means
P24E3 means the NH3 sensor signal lies below the lowest value an intact sensor can deliver. Usual culprits are a short to ground between probe and its electronics module, a terminal pushed back in the connector or a defect inside the probe. On International trucks with the 2013 N13 engine, a matching condition is reported as SPN 5848 with failure mode 4, i.e. the signal voltage of the mid-bed ammonia sensor too low or grounded. No manufacturer publishes P24E3 itself. CARB requires out-of-range checks for emission sensors on heavy-duty engines. While the fault is present the controller cannot trust ammonia feedback and has to dose from its model. P24E4 is the high counterpart, P24E2 the plausibility fault.
P24E3 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P24E3
- Malfunction indicator lamp on
- Scan tool shows ammonia reading stuck at minimum
Common causes of P24E3
- Most likelyChafed harness between probe and sensor module shorting to ground
- PossibleInternal fault in the ammonia probe
- Less likelyCorroded or pushed-back terminal at the probe connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Nh3 sensor
What each part of P24E3 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| E3 | The exact fault in that area. |
What to do next
- Note P24E3 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P24E3
What does P24E3 mean?
P24E3 means "NH3 Sensor Circuit Low". P24E3 means the NH3 sensor signal lies below the lowest value an intact sensor can deliver. It is a generic code, so it means the same on every make.
Is it safe to drive with P24E3?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P24E3 fail an emissions test?
Yes, it can. P24E3 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P24E3 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P24E3 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.