B1255

Code

LAND ROVER B — Body

Sensor ambient temperature in the car - circuit open

Brand: LAND ROVER

Type: B — Body

Views: UK: 26 EN: 38 RU: 22

AI status

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Page language: EN

Causes

Open or broken wiring (connector to sensor)
Corroded or loose connector terminals
Failed ambient temperature sensor (open thermistor)
Poor ground or reference supply to the sensor
Faulty HVAC/BCM/IPC control module or internal connector fault

Symptoms

Ambient/outside temperature reading absent, fixed at extreme value, or displaying '--'
Climate control may not operate in expected automatic mode or may use incorrect logic
Driver information display shows incorrect outside temperature
Possible intermittent HVAC behavior tied to outside temperature

What to check

Read and record freeze-frame and any additional stored codes with a scan tool
Visually inspect sensor location (usually in front bumper/grille) and wiring for damage or corrosion
Check connector for water ingress, bent pins, corrosion or looseness
Backprobe sensor connector with ignition ON to verify reference voltage and ground presence
Measure sensor resistance at harness side with sensor disconnected (compare to expected values)
Continuity check from sensor connector to the control module connector

Signal parameters

Sensor type: typically an NTC thermistor (resistance decreases as temperature rises)
Common nominal resistance: ~10 kΩ at 25°C (varies by manufacturer) — consult vehicle-specific data
Typical signal behavior: variable resistance; module reads voltage across thermistor or ADC value
Open-circuit indication: very high resistance (>>100 kΩ) or 'OL', or signal voltage pinned near supply or open value
Expected voltage range (vehicle-specific): roughly 0.5–4.5 V depending on circuit and reference topology

Diagnostic algorithm

Confirm code with a scan tool, note freeze-frame and any related HVAC or module codes.
Perform a visual inspection of the sensor and wiring at the mounting location (look for damage, impact, water).
Disconnect sensor connector and inspect pins for corrosion, bent or pushed-out terminals; repair or replace connector as needed.
With ignition ON (engine off), backprobe the connector: verify reference voltage (if present) and good ground continuity to chassis ground and module ground.
Measure the sensor resistance at the harness end with the sensor removed; compare to specification (expect NTC behavior). If open (infinite/high resistance), replace sensor.
If sensor resistance is OK, check continuity and resistance between the harness connector and the HVAC/control module pins. Repair any opens or high-resistance sections.
If wiring and sensor check good, test the control module inputs/outputs or swap with a known-good module/sensor if possible. Consult wiring diagrams and module pinouts.
After repair or replacement, clear codes and verify repair by monitoring live ambient temp value and ensuring code does not return after test drive.

Likely causes

Sensor disconnected or physically damaged (visible plug-out)
Water ingress/corrosion at sensor connector (common on exterior sensors)
Wire chafing or break in harness between sensor and control module
Terminal pushed out of connector or bent pin
Failed sensor element (open thermistor)

Fault status

⚠️ Status

Ambient temperature sensor circuit open — open/high resistance detected in outside air temperature sensor circuit. HVAC/comfort control module has logged a fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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LAND ROVER

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B1255 — Sensor ambient temperature in the car - circuit open