Brake Booster Pressure Sensor Circuit Malfunction
What does C0105 mean?
The C0105 code means the vehicle's onboard diagnostic system has detected: Brake Booster Pressure Sensor Circuit Malfunction. This is a critical severity code.
Common Symptoms
- Hard brake pedal feel
- Brake assist not functioning
- ABS warning light on
- Longer stopping distances
- Electronic brake force distribution disabled
Probable Causes (Ranked by Likelihood)
- Failed brake booster pressure sensor Very High
- Vacuum leak at brake booster hose High
- Corroded sensor connector Moderate
- ABS module sensor input circuit failure Low
Step-by-Step Diagnostic Procedure
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Scan ABS module for booster pressure DTCs
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Read booster pressure sensor data with scan tool
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Check vacuum hose to brake booster for leaks
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Test sensor output voltage under various pedal pressures
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Inspect sensor connector for damage
Frequently Asked Questions
What is the brake booster pressure sensor?
It measures the vacuum or hydraulic pressure in the brake booster to determine the level of power assist being provided. The ABS module uses this data for brake assist and emergency braking functions.
Can I drive with a hard brake pedal?
Only for short distances and at low speeds. A hard pedal means reduced power assist, requiring much more effort to stop. Stopping distances will be significantly longer.
Is this related to the brake booster itself?
The sensor measures booster performance, but a failed sensor does not mean the booster has failed. However, if the booster itself has a vacuum leak, it can also trigger this code.