U061C: Lost Communication With Reductant Temperature Sensor A

What it means

The vehicle bus reports loss of communication with smart reductant (DEF/AdBlue) temperature sensor A. Heater control and freeze protection lose their primary feedback.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test

How it works

Smart reductant temperature sensor A sends DEF/AdBlue temperature data over the vehicle network. U061C sets when expected messages from sensor A stop arriving, leaving heater control and freeze protection without that sensor's temperature feedback.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Scan all modules for communication codes and note freeze-frame conditions to determine whether the fault began with a wider network or power problem.
2. Check live data for reductant temperature sensor A and compare its status with other temperature readings and the actual cold or warm condition.
3. Inspect sensor A's connector and bus wiring for heat damage, corrosion, loose terminals, or signs of an open or short.
4. Verify the sensor module's power and ground against the manufacturer's wiring information.
5. Test the network circuit to sensor A for continuity and shorts according to the manufacturer's procedure.
6. If power, ground, and wiring pass, check whether sensor A transmits; replace the module only after confirming it does not.

Common fixes

• Repair damaged wiring or connector terminals at reductant temperature sensor A.
• Restore the sensor module's power or ground.
• Repair an open or short in the network circuit.
• Replace sensor A's module if its power, ground, and network connections are good but it does not communicate.

Can I keep driving?

Avoid relying on normal DEF/AdBlue heating or freeze protection while this fault is active, especially in freezing weather. If a reductant warning or emissions restriction appears, limit driving and arrange diagnosis promptly.