Code
B0169
HUMMER
B — Body
In-car Temp Sensor Failure (passenger -not used)
AI status
Completed
Completed
100%
Causes
- Open or shorted passenger in‑car temperature sensor circuit
- Disconnected, corroded or damaged sensor connector
- Failed passenger cabin temperature sensor (thermistor)
- Wiring harness damage (chafed, pinched, short to ground or battery)
- Faulty HVAC/control module or software issue
- Poor body/chassis ground affecting sensor circuit
Symptoms
- HVAC auto temperature control may not regulate cabin correctly
- Incorrect or implausible cabin temperature reading on HVAC status screens
- Blower or vent behavior may be abnormal in automatic mode
- DTC lamp may be illuminated or control module has stored code
- No noticeable HVAC symptom if passenger sensor is not used by that vehicle
What to check
- Use a scan tool to read B0169 and any related HVAC/body codes and live data for the passenger temperature sensor signal
- Verify freeze frame data and when the code originally set
- Visually inspect sensor location, connector and harness routing for damage, corrosion or disconnection
- Backprobe the sensor harness with connector connected to measure reference voltage, signal voltage and ground
- Measure sensor resistance at the sensor (with connector unplugged) while changing ambient temperature to confirm thermistor response
- Perform a wiggle test on the harness while monitoring live data to check for intermittent faults
Signal parameters
- Sensor type: typically an NTC thermistor (resistance decreases as temperature increases)
- Expected behavior: measurable resistance that changes with temperature (consult OEM chart for exact ohms vs °C)
- Signal voltage: often a low‑voltage signal referenced to a control module (typical range ~0.5–4.5 V on many systems) — verify with OEM data
- Common fault signatures: open circuit (infinite resistance), short to ground (near 0 V), short to battery/5V (stuck high), no change in resistance with temperature
Diagnostic algorithm
- Confirm code with a capable scan tool and record freeze frame / live data for the passenger temp sensor circuit.
- Verify vehicle-specific information: determine whether the vehicle actually uses a passenger in‑car temp sensor or the circuit is intentionally unused. Check wiring diagrams and OEM documentation.
- Visually inspect sensor location (passenger dash area, center vent area or evaporator housing), connector and wiring for obvious damage, corrosion or disconnection.
- With ignition off, disconnect the sensor connector and inspect pins for corrosion, bent pins, or damage. Repair or replace connector as needed.
- Measure sensor resistance at the sensor with an ohmmeter (connector unplugged). Compare to OEM resistance chart, and verify resistance changes when warmed/cooled (breath test or heat gun at low setting).
- With connector reinstalled and ignition ON (engine off), backprobe harness and measure reference voltage, signal voltage and ground continuity. Check for stuck high/low voltages or missing reference.
- Perform wiggle test on harness while watching live data or voltages to identify intermittent wiring faults.
- If wiring and connector are good but sensor readings are out of range or non‑responsive, replace the passenger in‑car temperature sensor.
- If sensor and wiring check good, suspect HVAC/control module fault. Confirm with module bench data or replacement per OEM procedure before replacing the module.
- After repair, clear codes and verify proper operation in live data; recheck after a drive cycle if required.
Likely causes
- Connector unplugged or corroded at the passenger in‑car temperature sensor
- Broken or shorted signal wire between sensor and HVAC module
- Failed thermistor sensor (no resistance change with temperature)
- Control module reporting unused sensor as failed (module configuration/programmimg issue)
Fault status
Status
Stored when the HVAC/body control module detects an open, short, out‑of‑range or implausible signal from the passenger in‑car temperature sensor circuit. May also set if the module expects a sensor that is not present or is disabled.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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