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U12A4 Code - Lost Communication With Ammonia Sensor

- Code Popularity: 3,770 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC U12A4?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other 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)
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How to Fix the DTC U12A4?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U12A4 code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

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

Code U12A4 Description

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.

OBDII Code U12A4 - Lost Communication With Ammonia Sensor - AutoCodes.com
U12A4 Code - Lost Communication With Ammonia Sensor

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Code U12A4 comments

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