Code
B0159
HUMMER
B — Body
Outside Air Temperature Sensor Circuit Range/Performance
Views:
UK: 6
EN: 10
RU: 4
AI status
Completed
Completed
100%
Causes
- Faulty outside/ambient air temperature sensor (NTC thermistor or similar)
- Open, short, or high-resistance wiring between sensor and module
- Corroded or loose connector at sensor or module
- Water intrusion or damaged sensor housing
- Poor ground or supply voltage issue to the sensor circuit
- Body control module (BCM) / climate module input fault or software issue
Symptoms
- Outside/ambient temperature displayed incorrectly, erratic, or not updating
- Climate control may behave suboptimally (incorrect temperature compensation)
- DTC stored and complaint logged in BCM; possible service message on dash
- Intermittent faults that appear in certain weather or after washing
What to check
- Read and record the DTC, freeze-frame data and occurrence conditions with a scan tool.
- View live data: ambient/outside temperature sensor value and check for realistic changes when temperature changes.
- Inspect sensor location (usually front bumper/grille area) for physical damage or water entry.
- Visually inspect wiring harness and connectors for corrosion, bent pins, or damage.
- Backprobe sensor connector and measure signal voltage/resistance while changing ambient conditions (warm breath or ice pack).
- Perform continuity and short-to-ground/power checks between sensor and BCM connector.
Signal parameters
- Sensor type: usually an NTC thermistor (resistance decreases as temperature increases).
- Module expects a measurable resistance or 0–5 V signal proportional to temperature; varies by manufacturer.
- Typical behavior: resistance should change gradually with ambient temperature (no open/short).
- Open-circuit: extremely high resistance or no signal; Short-circuit: near 0 Ω or 0 V — both will set a range/performance code.
- If available, compare measured resistance/voltage to vehicle-specific factory chart (specs vary by model/year).
Diagnostic algorithm
- Confirm DTC B0159 with a scan tool and note freeze-frame/live data values and conditions when the code set.
- Perform a visual inspection of the sensor, mounting, and harness (look for damage, water, debris, crushed wires).
- Backprobe the sensor connector and monitor live data. Apply a known temperature change (warm breath or ice) and confirm the sensor value changes accordingly.
- Measure sensor resistance across its terminals at known ambient temperature and compare to manufacturer spec. If no spec available, verify resistance changes when temperature is changed.
- Check supply voltage and ground at the sensor connector (if the sensor requires a reference voltage).
- Perform continuity tests from the sensor connector to the BCM connector; check for shorts to ground or battery voltage.
- Repair any wiring/connectors found faulty (clean corrosion, repair broken wires, replace damaged connector or harness section).
- If wiring and connector are good but sensor readings are out of expected behavior, replace the outside air temperature sensor and retest.
- If problem persists after sensor replacement, consider BCM input fault or software: consult OEM bulletins, check related network communications, and test/replace BCM only after confirming wiring and sensor are good.
- Clear codes, verify live data and perform a road/soak test to ensure the fault does not return before closing repair.
Likely causes
- Failed or water-damaged outside air temperature sensor
- Connector corrosion or loose wiring at sensor (intermittent)
- Open/short in harness between sensor and BCM
- Faulty BCM input or module communication issue
Fault status
Status
B0159 — Outside Air Temperature Sensor Circuit Range/Performance: Sensor reading out of expected range or intermittent.
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
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