B1B7E

Code

LAND ROVER B — Body

Temperature control - rear left

Brand: LAND ROVER

Type: B — Body

Views: UK: 16 EN: 21 RU: 14

AI status

Completed

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Page language: EN

Causes

Faulty rear-left temperature sensor (thermistor)
Failed or sticking rear-left blend/temperature actuator
Open/shorted wiring or poor connector at sensor or actuator
HVAC control module or rear climate module fault
Loss of LIN/CAN communication to rear climate module
Software/calibration error or stored bad adaptation data

Symptoms

Rear left zone temperature does not match set temperature
Rear left zone displays incorrect temperature or 'error' message
No response when adjusting rear-left temperature control
Inconsistent or drifting temperature readings for rear left zone
Ducts blow incorrect temperature from rear left outlets
Related HVAC warning/message in instrument cluster (possible limp mode for that zone)

What to check

Read and record all HVAC and network codes with a capable scan tool; note freeze-frame/data
Confirm vehicle battery voltage is stable (12V+); check related fuses and relays
Visually inspect connectors and wiring to rear left sensor, actuator and rear climate module for corrosion, bent pins or damage
Verify communication on LIN/CAN bus (no U0xxx comm codes) and that rear climate module is present on the network
Compare rear-left zone behavior to other zones to isolate module vs sensor/actuator problem
Check for available technical service bulletins (TSBs) or software updates for HVAC systems

Signal parameters

Temperature sensor: typically NTC thermistor — resistance varies with temperature. Expect decreasing resistance as temperature rises; check manufacturer's spec (common range: ~1 kΩ–100 kΩ across extremes).
Sensor voltage (if sensor is part of voltage divider): typically within ~0.5–4.5 V depending on temp and module supply
Actuator control: 0–12 V supply for motor or PWM signal for stepper/servo type; verify battery +12 V supply and switched ground
Communication: LIN or CAN messages present at known idle voltages (LIN ~ 0–12 V wake/PWM, CAN recessive ~2.5 V); tool should show rear module data stream
Resistance/continuity: expect near-zero continuity for power and ground circuits, open/infinite for broken wires; compare to pinout diagrams

Diagnostic algorithm

Retrieve full HVAC and network DTC list. Note if multiple similar codes or communication faults are present.
Clear code and perform quick functional test: change rear-left temperature and observe module/actuator response and live data.
Visually inspect connectors, pins and wiring at rear-left sensor and actuator. Repair any corrosion, damage or loose pins.
With ignition on, backprobe sensor connector and measure: supply voltage, ground presence, and signal voltage or resistance to ground per manufacturer specification.
Measure sensor resistance at ambient temperature and compare to expected thermistor values (or compare to identical sensor on another zone if available).
Command actuator via scan tool (if supported) and observe physical movement; check actuator power and control signal (PWM/voltage).
Check LIN/CAN communication: verify the rear climate module appears on network and is transmitting expected PID data. Investigate any U-codes (lost comm).
If wiring and connectors test good but sensor/actuator out of spec, replace the faulty component and retest.
If components and wiring are good but fault persists, update module software/calibration and perform adaptation procedure if required by manufacturer.
After repair, clear codes and verify repair by running system through temperature control range and confirming no reoccurrence.

Likely causes

Corroded/loose connector at rear left temperature sensor or actuator
Damaged wiring harness (pinched/rodent/abrasion) between rear module and sensor
Failed temperature sensor (out of spec resistance/voltage)
Actuator has failed or mechanical obstruction prevents movement
Control module firmware glitch or intermittent communication error

Fault status

⚠️ Status

Rear-left temperature control fault detected — sensor/actuator/communication abnormality in rear left climate control zone.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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B1B7E — Temperature control - rear left