VOLVO
ECM-0557 - Brake booster pressure sensor circuit too low.
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module sees the brake servo sensor circuit reading too low while the engine runs, and then sets the fault. The cause may be a wire shorted to ground, damaged wires or connectors, a damaged vacuum system, or a damaged control module.
Possible causes
- Wire short-circuited to ground
- Damaged wires or connectors
- Damaged vacuum system between the non-return valve and the brake servo
- Damaged engine control module
What you can do
- 1Save the fault codes and their values before erasing anything, since erasing removes all fault codes in the engine control module
- 2Check the vacuum sensor connector for looseness, contact resistance and oxidation
- 3Use a multimeter to check that the wire to the pressure sensor circuit is not shorted to ground and has no open circuit
- 4Check the hoses and connections to the brake servo for leaks
- 5Because the brake servo is part of the brake system, have a workshop check the vacuum system and wiring if the fault remains
Symptoms you may notice1
- No noticeable symptoms for the driver
General guidance for car owners. Diagnosis on the car can point to a different cause.