Powertrain, generic (extended)

P24EE NH3 Sensor Processor Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P24EE says the microcontroller inside the NH3 sensor module has failed its own self-test, for example a watchdog reset, a RAM or ROM error or a timing fault. The engine controller only learns this through the status the sensor sends, because the processor is what runs the probe, the heater and the J1939 messages. Navistar explains for the 2013 N13 that its mid-bed ammonia sensor diagnoses itself and that probe and module are separate parts, ordered individually; a processor fault therefore normally means replacing the module. Repeated resets can also come from an unstable supply, so check that first. No manufacturer documents P24EE publicly. CARB requires fault detection on heavy-duty sensors. P24ED is the memory fault.

Likely causes

Electronics of the NH3 sensor module failed
Unstable supply voltage causing processor resets
Module damaged by heat or water ingress

Symptoms

  • Check engine light on
  • NH3 sensor data missing or frozen

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€300–1,400
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

nh3 sensorsensor microcontroller

Related codes

P24EDP24E1

References: law.cornell.edu, static.nhtsa.gov.