P0557
PowertrainBrake Systemhigh severityBrake Booster Pressure Sensor Circuit Low
What P0557 Means
The signal voltage from the brake booster pressure sensor is lower than the expected threshold. This often points to a short to ground or a failed sensor.
Symptoms
- Brake warning light on
- Reduced brake assist
- Stiff brake pedal
Common Causes
- Short to ground in sensor wiring
- Faulty pressure sensor
- Corroded connector
- PCM signal fault
Diagnostic Steps
- Retrieve trouble codes
- Check sensor signal voltage
- Inspect wiring for shorts to ground
- Replace sensor if circuit checks good
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
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SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
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