Powertrain, generic (extended)

P24E5 NH3 Sensor Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P24E5 covers an NH3 sensor signal that jumps or drops out for short moments while staying mostly in range. Vibration, heat cycling of the exhaust and road salt make loose connector pins and cracked insulation near the SCR can the main suspects. Ram fitted such a sensor to the 2014 3500 to 5500 cab chassis with the 6.7 L Cummins; bulletin 18-042-20 offers one engine calibration for trucks that keep it and another for trucks where it was removed, and warns that implausible-data or lost-communication codes appear when the wrong one is loaded. No manufacturer documents P24E5 publicly. CARB asks for erratic-signal detection on heavy-duty emission sensors. Steady faults are P24E3 and P24E4.

Likely causes

Loose or corroded pins at the sensor or module connector
Harness insulation cracked by exhaust heat and vibration
Sporadic internal fault in the sensor electronics

Symptoms

  • Warning lamp that comes and goes
  • Live data shows spikes in the ammonia value

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–1,400
Time0.5–3 h

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

Parts involved

nh3 sensorsensor wiringsensor connector

Related codes

P24E1P24E2P24E3P24E4

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