BMW DTC C0021 – Brake Booster Performance
DTC C0021 meaning on BMW
The DTC C0021 on a BMW indicates a fault related to the performance of the brake booster. The brake booster is a critical component of the braking system that assists in applying the brakes with less effort from the driver. When this DTC is triggered, it means that the brake booster is not functioning as expected, which can affect the overall braking performance of the vehicle.
BMW DTC C0021 symptoms
Symptoms of the DTC C0021 on a BMW may include:
- Increased brake pedal effort required to stop the vehicle
- Brake pedal feeling spongy or hard
- Decreased braking performance
- ABS warning light illuminated on the dashboard
BMW DTC C0021 causes
Common causes of the DTC C0021 on a BMW include:
- Faulty brake booster
- Leaking vacuum lines connected to the brake booster
- Issues with the brake booster sensor
- Problems with the brake booster vacuum pump
BMW DTC C0021 seriousness
The DTC C0021 related to the brake booster performance is a serious issue as it directly affects the vehicle’s braking system. Driving with a faulty brake booster can compromise the safety of the vehicle and its occupants. It is crucial to address this issue promptly to ensure proper braking function.
How to diagnose DTC C0021 on BMW
To diagnose the DTC C0021 on a BMW, a mechanic may perform the following steps:
- Use a diagnostic scanner to retrieve the fault codes
- Inspect the brake booster for any visible signs of damage or leaks
- Check the vacuum lines and connections for leaks or blockages
- Test the brake booster sensor for proper operation
How to fix DTC C0021 on BMW
To fix the DTC C0021 on a BMW, the following steps may be taken:
- Replace the faulty brake booster with a new one
- Repair or replace any leaking vacuum lines connected to the brake booster
- Address any issues with the brake booster sensor
- If necessary, replace the brake booster vacuum pump
How to erase DTC C0021 on BMW
To erase the DTC C0021 on a BMW, the fault codes can be cleared using a diagnostic scanner. After the necessary repairs have been made to address the brake booster performance issue, the fault codes can be reset to turn off the warning light and ensure that the system is functioning properly.
Recommended tools & DTC Scanners for BMW
Best Diagnostic App for modern BMWs: BimmerLink
Recommended Bluetooth adapter for Bimmerlink: OBDLink CX
Cable adapter for Bimmerlink: Enet Cable USB Type C
For older BMWs we recommend: Autel AutoLink AL319 (2024 version)
Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter
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