What it means
The control module monitors the humidity sensor signal for stability. It sets this code when the signal drops out or changes erratically.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The cabin humidity sensor provides a changing moisture reading that the control module uses for automatic climate-control decisions. This code is set when that signal drops out or fluctuates unpredictably, often because a loose or vibration-sensitive connection briefly interrupts it.
Common causes
Most likely first.
- Connector loose or corroded
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check-engine light on
- Automatic climate control may work inconsistently
- Windshield may fog more easily
How to diagnose it
- Record freeze-frame data and watch the humidity sensor value on a scan tool while the climate system is operating for dropouts or abrupt jumps.
- Inspect the sensor connector for looseness, corrosion, moisture, or terminals that do not grip their pins firmly.
- Check whether the harness touches a vibrating component or is stretched, pulled, or rubbing near the sensor.
- With the wiring diagram, check continuity and the sensor supply and ground while gently moving the harness to reproduce an intermittent fault.
- If the signal remains erratic with stable wiring and connections, test the humidity sensor against the manufacturer's specification.
Common fixes
- Reseat and secure the humidity sensor connector.
- Clean corroded terminals or repair terminals with weak contact.
- Secure and reroute the harness away from vibration and abrasion.
- Replace the humidity sensor if its output still drops out with a stable circuit.
Can I keep driving?
Engine operation is usually unaffected, but climate control may behave inconsistently and the windshield may fog more easily. Do not continue driving if fogging impairs visibility.
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.