U0693

Code

Generic U — Network/User

Lost Communication With Humidity Sensor

Brand: Generic

Type: U — Network/User

Views: UK: 11 EN: 16 RU: 12

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in sensor data bus (CAN, LIN or proprietary network)
Faulty humidity sensor/module
Poor power or ground to the humidity sensor
Corroded, loose or damaged connector or wiring
Module awake/sleep or software/configuration mismatch
Network bus off condition or intermittent network noise

Symptoms

DTC U0693 stored or active
HVAC may revert to default mode or show incorrect automatic climate/defog behavior
Climate system shows reduced or delayed humidity control
Possible related errors or warnings in HVAC or vehicle body control modules
Intermittent or permanent loss of humidity data in scan tool live data

What to check

Read freeze frame and related network/memory codes with a scan tool
Confirm whether the humidity sensor appears in live data and note update rate
Visually inspect sensor connector and wiring for corrosion, damage, or water intrusion
Check sensor supply voltage and ground with key on (reference service manual for expected values)
Scan for bus-off or other module communication faults on CAN/LIN
Wiggle harness while monitoring live data to reproduce intermittent faults

Signal parameters

Expected message presence: periodic humidity sensor message on vehicle network (CAN/LIN)
Typical message rate: often 1–10 Hz (check vehicle-specific spec)
Data payload: humidity reported as %RH (0–100%) — may be 1 or 2 bytes depending on implementation
Supply voltage: commonly 5V or 3.3V reference for sensor electronics (verify in service manual)
Bus voltage: CAN dominant/recessive ~2.5V differential idle; LIN single-wire ~battery when idle — verify with scope if needed
No response or CRC/format errors indicate communication or module failure

Diagnostic algorithm

Retrieve and record all related DTCs and freeze-frame data. Note when code sets and any correlated events.
Attempt to view humidity sensor live data with a scan tool. Note if data is present, stale, or absent.
Cycle ignition and clear codes. Re-check whether code returns and whether it is intermittent or permanent.
Visually inspect sensor and harness for damage, corrosion, water ingress, or connector pins pushed out.
With connector disconnected, inspect pins for corrosion or bent pins. Reconnect firmly and recheck.
Backprobe sensor connector (or remove sensor if required) and measure supply voltage and ground with key on; compare to spec.
Monitor network with scan tool or oscilloscope: check for expected message ID, frequency, and signal integrity (CAN differential signals or LIN waveform).
If network messages from sensor are absent but supply and ground are correct, consider replacing the humidity sensor with a known-good unit or bench test the sensor per service procedures.
If network shows bus-off or excessive errors, isolate other modules on bus by disconnecting segments one at a time or using a bus terminator; repair the module causing noise/errors.
If wiring or connector fault found, repair/replace wiring harness or connector. After repair, clear codes and perform system test (drive cycle) to confirm repair.
If hardware is good but messages still absent, check for control module/gateway configuration and software updates; apply OEM software updates if required.
After repairs, clear the code and verify the humidity sensor data updates normally and the U0693 code does not return.

Likely causes

Disconnected or corroded connector at the humidity sensor
Damaged shield or shorted CAN/LIN wires due to rubbing or pinch
Humidity sensor lost internal power or ground
Sensor failed internally and stopped sending messages
Control module or gateway filtering sensor messages (software issue)
Bus-off state on the network due to another module fault

Fault status

⚠️ Status

Lost communication with humidity sensor — sensor messages not received or invalid on vehicle data bus. Check sensor, wiring, power/ground, and network integrity.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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