What it means
The vehicle bus reports loss of communication with smart humidity sensor (intake air or cabin). Humidity-based fueling and HVAC strategies switch to a substitute value.
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
The smart humidity sensor measures moisture in intake air or the cabin and sends its readings to other vehicle modules over the data bus. This code sets when the receiving module can no longer communicate with that sensor, so humidity-based fueling or climate-control strategies may use a substitute value.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- 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
- Record freeze-frame data and scan all modules for related communication codes to see whether the humidity sensor alone or a wider part of the bus is affected.
- Use live data to check whether the humidity reading is missing, fixed, or marked invalid while other sensor readings update.
- Inspect the humidity sensor connector and nearby bus wiring for looseness, corrosion, water intrusion, or damage.
- Check that the sensor has its specified power and ground, since a missing supply can make a healthy sensor disappear from the bus.
- Test the bus wiring for an open or short using the vehicle wiring diagram and manufacturer procedures.
- If wiring, power, and ground are sound, determine whether the sensor module itself has failed before replacing it.
Common fixes
- Reconnect or clean a loose or corroded humidity-sensor connector.
- Repair damaged or shorted bus wiring to the humidity sensor.
- Restore the sensor’s power or ground connection.
- Replace the humidity sensor module if its circuit and wiring are sound.
Can I keep driving?
If the engine runs normally and climate control works, a short trip may be possible, but monitor for warning lights or changes in drivability. Have it checked soon because incorrect humidity data can affect fueling or cabin climate functions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.