U12A4
Lost Communication With Ammonia Sensor
U12A4 is an OBD-II diagnostic trouble code meaning: Lost Communication With Ammonia Sensor. Common causes: ammonia sensor malfunction, open or short circuit in sensor wiring. Estimated repair cost: $56–278.
Symptoms
- Check Engine Light Illuminates
- Reduced engine performance
- Increased fuel consumption
- Problems with the SCR system
- Error messages on the dashboard
Causes
- Ammonia sensor malfunction
- Open or short circuit in sensor wiring
- Problems with sensor connectors
- Engine control module (ECU) malfunction
- Problems with the CAN data bus
How to Fix
- Check the ammonia sensor wiring and connectors for damage.
- Test the ammonia sensor with a multimeter.
- Check the CAN data bus for problems.
- Replace the ammonia sensor if it is faulty.
- Check the ECU for errors and update the software if necessary.
Related codes
FAQ
What does the U12A4 code mean?
U12A4 is an OBD-II diagnostic trouble code that indicates: Lost Communication With Ammonia Sensor
What causes a U12A4 error code?
The most common causes of U12A4 include: Ammonia sensor malfunction; Open or short circuit in sensor wiring; Problems with sensor connectors; Engine control module (ECU) malfunction.
How do I fix a U12A4 diagnostic trouble code?
To fix U12A4: Check the ammonia sensor wiring and connectors for damage.. Test the ammonia sensor with a multimeter.. Check the CAN data bus for problems.. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U12A4?
Yes, but get it checked soon
How much does it cost to fix U12A4?
The estimated repair cost for U12A4 is $56–278. Actual cost depends on your vehicle, location, and labor rates.
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