Possible Causes
WARNING: This page is about a different car, the 2018 Lincoln MKC. However, it is still accessible from the selected car via links, so may be relevant.
- Vacuum leak
- Vacuum hose obstruction
- Vacuum pump
- Brake booster
- AH1: CHECK FOR VACUUM LEAKS
- Ignition ON, engine running.
- Inspect the vacuum hose and each hose connection from the vacuum pump to the brake booster for leaks.
- Are any vacuum leaks found?
Yes No REPAIR the vacuum leak or INSTALL new components as necessary. For vehicles with a Duratec engine, INSTALL a new brake booster. REFER to Power Brake Actuation - Brake Booster .
For vehicles with an EcoBoost engine, Go to AH2.
- AH2: CHECK THE VACUUM PUMP OUTPUT
- Ignition OFF.
- Disconnect the vacuum hose from the brake booster.
- Connect a vacuum gauge to the vacuum hose.
- Ignition ON, engine running.
- Monitor the vacuum gauge.
- Does the vacuum gauge display greater than 600 mBar (18 In-Hg)?
Yes No INSTALL a new brake booster. REFER to Power Brake Actuation - Brake Booster . INSTALL a new vacuum pump. REFER to Power Brake Actuation - Brake Booster .