From Ross-Tech Wiki
17887/ P1479/005241 - Brake Boost Vacuum System: Mechanical Failure
- Fuse(s) faulty
- if the blade wheel (rotor) in the vacuum pump is stuck, most probably a fuse will burn
- Hoses from/to Brake Boost Vacuum Pump faulty
- Brake Boost Vacuum Pump faulty
- the blade wheel (rotor) in the vacuum pump is stuck
- Check / replace fuses
- check if the blade wheel (rotor) of the vacuum pump is stuck, otherwise the fuse will burn again
- Check Hoses from/to Brake Boost Vacuum Pump
- Check Brake Boost Vacuum Pump
- check if blade wheel (rotor) is stuck
- Perform Output Test
- Perform Short Trip in Basic Settings. Group 008 is commonly the self test for this system and may be activated Key On, Engine Off. If needed activate basic settings using [On/Off/Next] and pump the brake pedal.
- When this fault is stored in conjunction with misfire and system lean fault codes check the PCV system and any other possible sources of engine mechanical vacuum leaks. Although PCV failure is most common on the 1.8T engines equipped with the auxiliary vacuum pump, any engine with low vacuum can cause that electric pump to run excessively - resulting in this fault code.