B150612

Code

VOLVO B — Body

Inside Temperature Sensor Surface Temperature Sensor. Circuit Short To Battery

Brand: VOLVO

Type: B — Body

Views: UK: 18 EN: 28 RU: 27

AI status

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Page language: EN

HVAC/comfort system displays incorrect inside temperature or a fixed high reading
Automatic climate control running incorrectly (overheating or always warm)
Fault code stored for inside temperature sensor and possible related HVAC warnings
Inconsistent or frozen temperature display on instrument cluster/AC menu

Visual inspection of sensor and wiring harness for chafing, heat damage, pin corrosion or water entry
Check connector mating — pins straight, fully seated and corrosion‑free
Scan tool: read live data for inside temperature sensor and freeze frame data
With ignition ON, backprobe sensor harness and measure signal voltage with sensor connected and then disconnected
Check for battery voltage on the sensor signal pin when the sensor is disconnected (indicates short to battery or stuck high-side)
Measure continuity between signal wire and battery positive (should NOT be direct short)

Sensor type: typically an NTC thermistor (resistance varies with temperature)
Reference/supply: sensor circuit typically uses a module-supplied pull-up or reference (commonly 5 V system)
Expected signal: temperature-dependent voltage (varies roughly across the mid-range of the reference — consult service manual for exact values)
Failure signature: near battery voltage on sensor signal pin (short to battery) or fixed high voltage regardless of temperature

Retrieve and record freeze frame/live data for the inside temperature sensor. Note displayed temp and any related codes. 2) Visually inspect sensor location and harness for damage, heat, fluid exposure and poor repairs. 3) With ignition ON and HVAC system in a mode that powers the sensor, backprobe the sensor signal pin at the harness connector and measure voltage with sensor connected; note reading. 4) Disconnect the sensor and measure voltage on the signal pin again. If battery voltage is present with sensor disconnected, suspect a short to battery or a stuck module output. 5) Check continuity between the signal wire and battery positive; a low-resistance path indicates a short. 6) Measure sensor resistance directly (remove sensor) at ambient temperature and compare to service specification or expected thermistor behavior (resistance changes with temperature). 7) Wiggle the harness and connectors while monitoring signal for intermittent shorts. 8) If wiring/connector shows short, repair or replace affected section and re-check. If wiring is good and the sensor reads correctly off-vehicle, suspect module fault. 9) After repair or replacement, clear codes and test by observing live data and performing a functional drive/operation to confirm code does not return.

Wiring harness damaged near sensor (rub through to a battery feed)
Corroded/contaminated sensor connector allowing short to battery
Failed sensor internal short
Connector pin pushed into housing making contact with battery feed or adjacent pin

⚠️ Status

Inside temperature (surface) sensor circuit: short to battery detected. Code stored in climate/control module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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.

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