What does it mean?
U1186 is a Network (CAN bus, module communications) fault code. It indicates: Lost Communication With Adaptive Cruise Control Module .
Symptoms
- Message that adaptive cruise control is unavailable, and the system will not switch on
- Cruise control cannot be set, or reverts to a basic function without distance keeping
- Forward collision warning and automatic emergency braking disabled at the same time
- Warning lamps for the driver assistance systems illuminated
- The distance and following gap display missing from the cluster
- The fault appears after front end repair work or a low speed impact
Likely causes
- Impact damage or a knock to the front bumper area that has moved or damaged the sensor
- Corroded or wet connector at the sensor, since it sits low and exposed at the front of the car
- Damaged wiring in the front harness after a minor collision, bumper removal or rodent activity
- Blown fuse or a poor power feed and ground at the sensor module
- Open or shorted bus wiring between the sensor and the powertrain or chassis network
- Sensor replaced or the bumper refitted without carrying out the required aiming and calibration
- Internal failure of the radar sensor module
How to fix it
- Scan all modules and check whether the radar sensor is the only unit missing
- Inspect the front bumper area for impact damage, and check that the sensor and its bracket are secure and correctly positioned
- Unplug and inspect the sensor connector for corrosion, water and bent pins
- Check the fuse and measure supply voltage and ground at the sensor connector under load
- Test the bus wiring from the sensor back to the network for opens, shorts and chafing along the front harness
- Carry out the sensor aiming and calibration procedure if any front end work has been done
- Replace the radar sensor module only after wiring and supply test good, then calibrate it and verify the system on a road test