Engine-Codes - Jeep - U12A4 JEEP

U12A4 JEEP - Lost Communication With Ammonia Sensor

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What is this?
Table of contents

U12A4 JEEP Possible Causes

  • Faulty Ammonia Sensor Module
  • Ammonia Sensor Module harness is open or shorted
  • Ammonia Sensor Module circuit poor electrical connection
  • Faulty Powertrain Control Module (PCM)

How is the U12A4 JEEP code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

What is the cost to diagnose the U12A4 JEEP code

Labor: 1.0

The cost to diagnose the U12A4 JEEP code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
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Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

U12A4 JEEP Meaning

The Ammonia (NH3) Sensor is located in the middle of the aftertreatment SCR Catalyst and is used to measure the ammonia concentration in the aftertreatment system. The Ammonia Sensor Module is a smart device that performs its own internal diagnostics, as well as diagnostics on the sensor and reports malfunctions back to the Powertrain Control Module (PCM) via the J1939 data link. The PCM will illuminate the Malfunction Indicator Lamp (MIL) after the diagnostic runs and fails in one drive cycle.

More Information

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