B150E49

Code

VOLVO B — Body

Defog Sensor. Internal Electronic Failure

Brand: VOLVO

Type: B — Body

Views: UK: 18 EN: 23 RU: 20

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Defog sensor internal electronic component failure
Corroded, damaged or loose connector
Open, shorted or high-resistance wiring between sensor and HVAC/control module
Lost or intermittent power supply or ground to the sensor
Communication bus error (LIN/CAN) or module software issue
Water/contamination ingress or physical damage to sensor

Symptoms

DTC B150E49 stored in HVAC/Body control module
Defog/anti-fog function may be disabled or operate poorly
Climate control displays a sensor or HVAC fault message
Intermittent or no response from automatic defogging
Possible related communication errors logged (lost sensor data)

What to check

Read and record all related DTCs and freeze frame data with a compatible Volvo scan tool
Visual inspection of sensor, connector and wiring for corrosion, damage or water ingress
Check connector engagement and push-pull test for secure pins
Measure supply voltage to sensor with ignition ON (see signal params)
Check ground continuity from sensor ground to chassis
Scan for related communication errors on LIN/CAN bus

Signal parameters

Supply voltage: nominal vehicle battery voltage (~11–14.5 V) with ignition ON
Ground: continuity to chassis; expected low resistance (
Signal type: often low-voltage analog (0–5 V) or digital via LIN/CAN depending on model — consult vehicle-specific wiring diagram
Idle/operational current: low; internal fault may show open/short or no response
Communication: if on bus, check for valid messages from sensor node and bus voltage levels (LIN ~12 V idle to ~0–5 V pulses; CAN differential ~2.5 V idle)

Diagnostic algorithm

Use dealer-level or capable scan tool to read B150E49 and any related codes; note freeze frame and clear codes.
Attempt to re-create fault by operating defog function and monitoring live data; if code returns, continue.
Visually inspect sensor location, mounting and connector for contamination, moisture, or physical damage; repair as needed.
With connector disconnected, verify supply voltage at sensor connector with ignition ON and HVAC active. Compare to signal_params.
Verify ground continuity from sensor ground pin to chassis ground (
If sensor communicates on LIN/CAN, check for bus activity and correct voltage levels at connector; use oscilloscope if available.
Check wiring continuity between sensor and HVAC module for opens/shorts using backprobe or harness diagrams.
If power/ground/communication and wiring are correct but fault persists, substitute a known-good sensor (or connector repair) to confirm internal failure.
If replacement sensor clears fault, reassemble and retest. If fault remains, inspect/replace HVAC/control module or repair bus wiring as indicated.
After repairs, clear codes and perform a full function test; record results and advise customer.

Likely causes

Sensor internal electronics failed (most likely)
Connector pins corroded or pushed out
Short to battery or ground on sensor signal or supply wire
HVAC control module not powering or polling the sensor
Aftermarket glass or repairs that disturbed sensor alignment/connection

Fault status

⚠️ Status

Defog sensor internal electronic failure detected — sensor not responding or internal circuitry fault. Check power, ground, connector and communication; replace sensor if internal failure confirmed.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-1.5 hours

Similar codes

Repair manuals

Manual library for VOLVO

221

Browse 221 VOLVO manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

VOLVO

Your experience will help others

+100 karma for a short comment :)

Was this AI description helpful?

Your feedback helps improve AI descriptions.

👍 Like 0 👎 Dislike 0

Send to email