HVAC In-Car Temperature Sensor Circuit Malfunction
What does B1315 mean?
The B1315 code means the vehicle's onboard diagnostic system has detected: HVAC In-Car Temperature Sensor Circuit Malfunction. This is a low severity code.
Common Symptoms
- Automatic climate control blows wrong temperature
- AC cycles on and off erratically
- Cabin temperature readout incorrect
- Heater runs in summer or AC runs in winter
- Climate control system slow to reach set temperature
Probable Causes (Ranked by Likelihood)
- Failed in-car temperature sensor Very High
- Clogged aspirator tube blocking airflow to sensor High
- Corroded sensor connector Moderate
- HVAC control module sensor input failure Low
Step-by-Step Diagnostic Procedure
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Check in-car temperature sensor reading with scan tool
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Inspect aspirator tube for blockage
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Test sensor resistance and compare to temperature chart
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Clean sensor and aspirator opening
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Check connector for corrosion or damage
Frequently Asked Questions
Where is the in-car temperature sensor?
It is typically located in the dashboard, often near the steering column or center console area. Look for a small grille or opening where air is drawn across the sensor by an aspirator fan.
What is an aspirator tube?
The aspirator tube uses a small vacuum or fan to draw cabin air across the temperature sensor. If this tube is blocked, the sensor cannot accurately measure the cabin temperature.
Can I use manual mode instead of automatic?
Yes. Switching to manual climate control mode bypasses the in-car temperature sensor and lets you directly control fan speed and temperature. This is a valid workaround until the sensor is fixed.