HVAC In-Car Temperature Sensor Circuit Malfunction
What does B1205 mean?
The B1205 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 not maintaining set temperature
- Cabin temperature fluctuates excessively
- Climate control blows too hot or too cold
- In-car temperature display incorrect
- A/C or heater running constantly
Probable Causes (Ranked by Likelihood)
- Failed in-car temperature sensor Very High
- Blocked aspirator tube to sensor High
- Aspirator fan not drawing air past sensor Moderate
- Damaged wiring to in-car sensor Moderate
- HVAC control module fault Low
Step-by-Step Diagnostic Procedure
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Check in-car temperature sensor reading with scan tool
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Inspect sensor location on dashboard or headliner
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Verify aspirator fan is operating
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Clean aspirator tube if blocked
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Test sensor resistance and compare to specifications
Frequently Asked Questions
Where is the in-car temperature sensor?
The in-car temperature sensor is typically located in the dashboard area, often near the steering column or in the headliner. It has a small aspirator fan that draws cabin air past it.
What is an aspirator tube?
The aspirator tube is a small hose that uses HVAC airflow to pull cabin air past the temperature sensor. If it is blocked or disconnected, the sensor cannot accurately measure cabin temperature.
Why does my automatic climate control not hold the right temperature?
If the in-car sensor reads incorrectly, the automatic climate control system will overcompensate -- heating when the cabin is already warm, or cooling when it is already cool.