What does it mean?
U1003 is a Network (CAN bus, module communications) fault code. It indicates: DIS Temperature Sensor Signal Error in Head Unit .
Symptoms
- Audio and display drop out after the system has been running for a while, then recover when cool
- Head unit reduces volume or shuts down and shows a temperature warning
- Screen dims or blanks on hot days or after long motorway drives
- Slow, laggy operation of the touch screen and menus
- Warm or hot console panel around the unit
- Fault rarely present on a cold start, appearing only once the cabin is hot
Likely causes
- Internal temperature sensor or its solder joint has failed inside the head unit
- Head unit genuinely overheating because its ventilation slots are blocked by trim, insulation or accessories
- Unit installed in a console with poor airflow, or a cooling fan inside the unit that has stopped
- Dust and debris packed into the heatsink area of the module
- Low or unstable supply voltage confusing the sensor reference
- Water or drink spillage into the console reaching the circuit board
- Corrupted software after an interrupted update, giving false sensor readings
How to fix it
- Confirm whether the complaint is heat related by noting when the fault appears; a hot-only fault supports a real overheating problem
- Remove the trim around the head unit and check that the ventilation openings and heatsink are clear of dust and insulation
- Verify nothing has been packed behind the unit, such as cables, mats or accessory boxes blocking airflow
- Read the sensor value in live data with the scan tool and compare it with a plausible cabin temperature
- Check the supply voltage and the ground at the unit, since a poor ground can distort internal references
- Inspect for spillage or water tracking on the console and dry the area if found
- Update the head unit software if a newer release exists
- Replace the head unit only after airflow, power, ground and software have all been verified as good