DTC Advanced Diagnostics: P0557
DTC P0557: Brake Booster Pressure Sensor A Circuit Low Voltage
General Description
The brake booster pressure sensor measures the change in the pressure of the brake booster. The signal from the brake booster pressure sensor is low voltage at low pressure and high voltage at high pressure. The powertrain control module (PCM) compares the expected voltage to the brake booster pressure sensor output voltage. When the brake booster pressure sensor output voltage is lower than the expected voltage for a set time, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type, OBD Status
| Execution | Continuous |
| Sequence | None |
| Duration | 2 seconds or more |
| DTC Type | One drive cycle, MIL off* |
*: Auto idle stop indicator (amber) blinks.
Enable Conditions
| Condition | |
|---|---|
| Vehicle | ON mode |
Malfunction Threshold
The brake booster pressure sensor output voltage [BRAKE BOOSTER PRESSURE SENSOR (A) VOLTAGE] is 0.43 V or less for at least 2 seconds.
[ ]: HDS Parameter
Possible Cause
- Brake booster pressure sensor VCC line open
- Brake booster pressure sensor MPMON line short to ground
- Brake booster pressure sensor failure
- PCM internal circuit failure
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected, the auto idle stop system indicator (amber) comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory. The MIL does not come on.
Conditions for clearing the DTC
The auto idle stop system indicator (amber) is cleared if the malfunction does not return in next trip in which the diagnostic runs. The auto idle stop system indicator (amber), the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.