Code
B0158
OPEL
B — Body
Outside Temperature Sensor Circuit Low Voltage
Views:
UK: 7
EN: 11
RU: 6
AI status
Completed
Completed
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Causes
- Short to ground in sensor signal or harness
- Open or high-resistance connection to sensor supply or signal
- Corroded, damaged or loose sensor connector
- Failed outside temperature (NTC) sensor
- Faulty module/ECU reference voltage or internal fault
- Blown fuse or poor ground for the related module
Symptoms
- Incorrect or unusually low outside temperature reading on the instrument cluster or HVAC display
- Outside temperature reading frozen or showing extreme low value
- Possible reduced functionality of climate control that uses outside temp data
- Related DTCs stored for temperature sensor circuits
What to check
- Read DTC and freeze-frame data with a scan tool; capture live outside temperature sensor voltage/values
- Visually inspect sensor, connector, and wiring for corrosion, damage or moisture
- Backprobe sensor connector and measure signal voltage with ignition ON
- Measure sensor resistance at the connector (cold and room temp) and compare to expected NTC behavior
- Verify module reference voltage and ground continuity
- Wiggle harness while monitoring live data to reproduce fault or change signal
Signal parameters
- Sensor type: usually NTC thermistor (resistance varies with temperature)
- Typical reference/supply voltage to sensor circuit: around 5 V (verify with vehicle-specific data)
- Expected signal voltage range: ~0.2 V (very cold) to ~4.5 V (warm) depending on sensor design; low voltage indicates signal pulled toward ground
- Typical resistance at 25°C for common outside temp sensors: ~10 kΩ (varies by manufacturer) — resistance increases as temperature falls
- Exact voltage/resistance curve is vehicle- and sensor-specific; consult Opel wiring/service data for pinout and values
Diagnostic algorithm
- Verify the DTC: connect scan tool, confirm B0158 and note freeze-frame/live data values.
- Visual inspection: examine the outside temp sensor, mounting point and harness for damage, corrosion or water ingress. Repair obvious damage.
- Check connector: disconnect the sensor, inspect terminals, clean if corroded, then reconnect securely.
- Measure supply and signal: backprobe sensor connector with ignition ON. Verify reference voltage from the module and the sensor signal voltage. Compare to expected values.
- Measure sensor resistance: unplug sensor and measure resistance across sensor pins at known ambient temperature (room temp and, if needed, ice water). Confirm NTC behavior (resistance should change with temperature).
- Check continuity and shorts: test wiring for short to ground or short to power and for open circuits between sensor and module. Repair wiring as required.
- Check grounds and fuses: verify proper ground connections and relevant fused supplies to the controlling module.
- Replace suspect parts: if wiring and supplies are correct but readings are out of range, replace the outside temperature sensor. If replacement does not correct, consider module fault and consult manufacturer service information.
- Clear codes and test: clear the DTC, run vehicle through conditions to verify the fault does not return and that outside temperature reading is plausible.
Likely causes
- Damaged wiring harness (abrasion, pinched, chafed) shorting signal to ground
- Corroded connector terminals at the sensor (moisture exposure)
- Sensor failed (stuck low resistance or open)
- Module supply or reference voltage fault
- Poor chassis or module ground
Fault status
Status
Outside temperature sensor circuit voltage lower than expected — signal indicates low voltage or short to ground. Check sensor, wiring, connectors, and module reference/ground.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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