What does it mean?
U1190 is a Network (CAN bus, module communications) fault code. It indicates: Lost Communication With Humidity Sensor .
Symptoms
- Windows fogging up much more easily because automatic demisting no longer works
- Air conditioning compressor running constantly or not engaging when it should
- Automatic climate control behaving oddly, with airflow and temperature changing for no reason
- A message about the climate system on the display
- Interior humidity or dew point values missing from live data
- The fault often appears after a windscreen replacement or a water leak
Likely causes
- Sensor not properly seated against the glass or its bracket left loose after a windscreen replacement
- Connector at the sensor loose, corroded or not fully latched
- Open or shorted wire between the humidity sensor and the climate control module
- Missing supply voltage or a poor ground at the sensor
- Water leaking down from the windscreen seal or the roof aerial area onto the sensor
- Internal failure of the humidity sensor, which can also follow long term condensation
- Climate control module fault or outdated software
How to fix it
- Read climate control live data and confirm whether the humidity value is missing, frozen or implausible
- Remove the mirror cover and check that the sensor is correctly clipped to its bracket and in proper contact with the glass
- Unplug and inspect the connector for corrosion, moisture and spread terminals, then reseat it
- Measure supply voltage and ground at the sensor and check the data line to the climate module for continuity and shorts
- Look for water leaks around the windscreen, roof aerial and headliner that could reach the sensor
- Compare with the interior temperature sensor readings to judge whether the values are plausible
- Replace the humidity sensor only after wiring and mounting have been checked, then confirm auto demist operation