P24E6 code meaning
NH3 Sensor Heater Circuit/Open
Powertrain system Generic code P24xx codes Check engine light
What P24E6 means
Like a NOx sensor, the ammonia sensor only measures once its ceramic element is hot, so it carries an electric heater. P24E6 reports that this heater circuit is open or otherwise electrically faulty: the driver commands heating but sees no current flowing. Common reasons are a burnt heater element, a broken wire in the pigtail or a terminal that lost contact. Without heat the probe stays cold and delivers no usable ammonia value, so dosing runs on the model alone. No manufacturer documents P24E6 publicly. CARB's heavy-duty rule requires a malfunction when heater current or voltage drop leaves the specified window. Low and high faults are P24E7 and P24E8; slow or unstable heating is P24E9.
P24E6 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P24E6
- Check engine light on
- No ammonia reading after warm-up
Common causes of P24E6
- Most likelyHeater element inside the NH3 probe burnt through
- PossibleBroken wire in the sensor pigtail near the hot exhaust
- Less likelyHeater terminal without contact in the connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Nh3 sensor heaterHeater driverSensor wiring
What each part of P24E6 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). |
| E6 | The exact fault in that area. |
What to do next
- Note P24E6 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 P24E6
What does P24E6 mean?
P24E6 means "NH3 Sensor Heater Circuit/Open". Like a NOx sensor, the ammonia sensor only measures once its ceramic element is hot, so it carries an electric heater. It is a generic code, so it means the same on every make.
Is it safe to drive with P24E6?
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 P24E6 fail an emissions test?
Yes, it can. P24E6 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 P24E6 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P24E6 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.