Code
B150E87
VOLVO
B — Body
Defog Sensor. Missing Message
Views:
UK: 11
EN: 20
RU: 14
AI status
Completed
Completed
100%
Causes
- Defog sensor failed or intermittent
- Faulty connector or corrosion at sensor
- Broken or shorted wiring between sensor and network/module
- Open/shorted CAN/LIN network or missing termination
- Blown fuse or lost sensor power/ground
- Faulty HVAC or gateway control module
Symptoms
- Automatic defog/auto climate defogging not functioning or disabled
- HVAC display may show sensor unavailable or error
- Interior windshield fogging not cleared automatically
- Related DTCs for network communication or HVAC functions
- Intermittent operation of defog function
What to check
- Read all modules with a capable scan tool; record DTCs and freeze frame
- Verify vehicle battery voltage and fuses for HVAC/sensor circuit
- Check for presence of the defog sensor message on the bus using a diagnostic tool or CAN/LIN data logger
- Visually inspect sensor connector and wiring for corrosion, damage or water ingress
- Backprobe sensor connector to check for proper power, ground and signal (if applicable)
- Inspect related modules (HVAC control module, body/gateway) for additional comms faults
Signal parameters
- Communication type: typically a network message (CAN or LIN) rather than an analog voltage
- Expected message: periodic update from defog/condensation sensor (frequency typically ~1 Hz or faster)
- Bus speeds: vehicle CAN commonly 250–500 kbps; message should appear on bus when ignition on
- Power: sensor may require switched 12 V and a ground; voltage should be near battery voltage with ignition on
Diagnostic algorithm
- Retrieve and record all DTCs from all modules. Note time since code set and any related network codes.
- Clear codes and perform an ignition cycle to see if B150E87 returns and under what conditions.
- Use a scan tool to watch live data and verify whether the defog sensor data/message is present and updating.
- If no message, inspect the sensor connector and harness for corrosion, bent pins, or water damage. Repair as needed.
- Verify sensor supply and ground at the connector with a meter. If power/ground missing, trace and repair fuse, relay or wiring.
- Check continuity between sensor and HVAC/gateway control module connector pins. Repair any opens/shorts.
- If wiring and power are good, replace the defog sensor with a known-good unit and re-test communication.
- If sensor replacement does not restore message, investigate module network interface (CAN/LIN) and related modules. Use scope or CAN bus tool to verify bus integrity and message IDs.
- If network fault or module software is suspect, check for technical service bulletins and perform module reprogramming or replacement per manufacturer guidance.
- After repairs, clear codes and verify normal operation and message presence during driving/test cycles.
Likely causes
- Corroded or disconnected connector at the defog sensor or harness
- Damaged wiring from moisture, chafing or pinched harness
- Sensor internal failure (no transmit)
- Loss of module power or ground feeding sensor
- Network communication fault (CAN/LIN) preventing message delivery
Fault status
Status
Defog sensor message missing on vehicle network — defog/condensation sensor data not received.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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