P055E - Brake Booster Pressure Sensor Circuit Intermittent/Erratic
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P055E is triggered when the Engine Control Unit (ECU) detects a signal from the Brake Booster Pressure Sensor that is inconsistent, intermittent, or erratic. This sensor monitors the vacuum level within the brake booster to ensure adequate power braking assistance. The fault is logged if the ECU detects sudden voltage spikes, drops, or values that are physically impossible given the current engine manifold vacuum. This often affects subsystems like Start/Stop strategy and emergency brake assist systems.
Possible Causes
Loose connection or oxidized terminals in the sensor connector.
Failing brake booster pressure sensor (internal intermittent short).
Damaged wiring harness (chafing) in the signal circuit.
Vacuum leaks in the booster or hoses causing turbulent pressure readings.
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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