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DTC codes / U06xx · Network communication / U0693

U0693Lost Communication With Humidity Sensor

U0693 is a generic network communication code indicating that a control module on the vehicle's data bus has lost contact with the humidity sensor. The module that monitors the sensor (often the body control module or climate control module) sets this code when it stops receiving expected messages or voltage signals from the humidity sensor for a calibrated period.

SystemNetwork
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • A warning light on the dashboard, usually the check engine light or a climate control system warning.
  • Automatic climate control may stop adjusting fan speed or air recirculation based on humidity.
  • The windshield may fog up more easily because the system no longer receives humidity data to trigger defog actions.
  • Remote start or automatic defrost features may be disabled or behave erratically.
  • Often no symptoms besides the warning light, especially if the humidity sensor is not critical to basic operation.

Common causes, most likely first

  1. A failed humidity sensor itself, which is the most common cause on vehicles that use a dedicated sensor.
  2. Corroded, loose, or damaged electrical connector at the humidity sensor.
  3. Broken, chafed, or shorted wire in the sensor circuit between the sensor and the control module.
  4. A control module that has lost power or ground, or has an internal fault affecting the sensor communication circuit.
  5. Water intrusion into the sensor or connector, often from a leaking windshield seal or clogged sunroof drain.
  6. A low or weak battery causing voltage drops that disrupt communication on the data bus.
  7. Aftermarket accessories or poor previous repairs that introduce electrical noise or incorrect resistance on the bus.

How to diagnose and fix it

  1. Inspect the humidity sensor and its connector for corrosion, moisture, or physical damage, and clean or dry as needed.
  2. Check the sensor circuit wiring for continuity, shorts to ground, and shorts to power using a multimeter and the vehicle's wiring diagram.
  3. Verify that the control module that sets the code has good power and ground connections, and check for any related communication codes.
  4. Test the humidity sensor's signal output if the manufacturer provides a specification, and replace the sensor if it is out of range.
  5. Clear the code and perform a road test or a scan tool relearn procedure to confirm the communication is restored.
  6. If the code returns after sensor and wiring repairs, check for software updates or known communication issues for the specific module.
  7. As a last step, substitute a known-good module only if all other circuits test good and the fault is isolated to the module.

Humidity sensor faults that fool technicians

  • A humidity sensor that is unplugged or missing its 5-volt reference will set U0693 even though the sensor itself is not defective, so always check for power and ground at the connector first.
  • Water leaks from a clogged cabin air intake or windshield cowl often corrode the humidity sensor connector and cause this code without any obvious moisture inside the cabin.
  • Some vehicles share the humidity sensor signal with the rain sensor or auto-dimming mirror, and a fault in those systems can set U0693 as a secondary code.
  • A weak battery or a failing alternator can cause intermittent communication codes like U0693 that disappear after a charging system repair, so load-test the battery before replacing parts.
  • The code does not always mean the sensor is bad; a control module that is asleep or has a low-voltage wake-up issue can also stop polling the sensor and set this code.

Can I keep driving with U0693?

The vehicle remains safe to drive because the humidity sensor only affects climate control convenience features, not engine or safety systems. You can continue driving, but avoid relying on automatic defog or recirculation functions until the fault is repaired.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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