Pinpoint Test B : P0555, P0557, P0558, P0559: Notes
Refer to Electronic Engine Controls - 2.0L Duratec for schematic and connector information.
Normal Operation and Fault Conditions
The PCM uses the brake booster vacuum sensor to detect a low vacuum condition in the brake booster. The engine is equipped with a mechanical vacuum pump driven by the cam shaft. When the auto stop-start system is engaged and the engine is stopped, if the PCM detects a low vacuum condition in the brake booster, the engine is restarted to allow vacuum to build in the brake booster. This condition can lead to the auto stop-start system immediately restarting the engine after it shuts off. There are no warning indicators or messages in the message center to indicate a concern.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P0555 | Brake Booster Pressure Sensor Circuit | This DTC sets when there is a circuit concern (open circuit, short to ground or short to open) in the brake booster vacuum sensor circuits. |
| P0557 | Brake Booster Pressure Sensor Circuit Low | This DTC sets when the vacuum sensor return voltage is below a predetermined threshold. |
| P0558 | Brake Booster Pressure Sensor Circuit High | This DTC sets when the vacuum sensor return voltage is above a predetermined threshold. |
| P0559 | Brake Booster Pressure Sensor Circuit Intermittent | This DTC sets when the vacuum sensor data meets certain criteria indicating an intermittent circuit concern. |
Possible Causes
- Wiring, terminals or connectors
- Brake booster vacuum sensor