What Does P0558 Mean?
The ECM has detected that the brake booster pressure sensor circuit is producing a voltage above the maximum acceptable threshold. This high-input condition typically indicates an open ground circuit, an open signal wire, or a failed sensor with high internal resistance. The ECM interprets this as a no-vacuum or maximum-pressure condition regardless of actual brake booster status.
Safety Warning
A stuck-high signal causes the ECM to perceive no brake booster vacuum at all times, which may trigger false brake assist warnings and disable vacuum management features. The vehicle's actual braking remains functional but safety monitoring is compromised.
Common Causes
35%
Open ground wire at the brake booster pressure sensor causing the signal to float to reference voltage
30%
Failed brake booster pressure sensor with open internal sensing element causing high-impedance output
20%
Open signal wire between the brake booster pressure sensor and ECM allowing the signal to be pulled high by the ECM's internal pull-up
15%
Signal wire shorted to 5V reference or battery voltage through harness damage
Diagnostic Steps
1
Step 1: Inspect the brake booster pressure sensor connector for backed-out pins, spread terminals, or corrosion. Verify the connector fully latches and terminals make firm contact.
2
Step 2: With the sensor disconnected and key on, check the signal wire voltage at the ECM connector. Near 5V confirms the ECM pull-up is functioning and the fault is in the sensor or ground circuit.
3
Step 3: Measure continuity of the ground wire from the sensor connector back to the ECM ground. An open ground (greater than 5 ohms) will cause the signal to float high. Also verify the sensor ground pin is not corroded or recessed.
4
Step 4: With the sensor disconnected, briefly jumper the signal pin to ground at the sensor connector. If the ECM reading drops to near 0V, the signal path to the ECM is intact.
5
Step 5: Replace the brake booster pressure sensor if it has failed open internally. Repair any open ground or signal wiring. Clear codes and verify proper sensor response across the full vacuum range.
Estimated Repair Cost
$60 - $300
Parts + labor, varies by vehicle and location
The ECM has detected that the brake booster pressure sensor circuit is producing a voltage above the maximum acceptable threshold. This high-input condition typically indicates an open ground circuit, an open signal wire, or a failed sensor with high internal resistance. The ECM interprets this as a...
The most common cause of P0558 (Brake Booster Pressure Sensor Circuit High Input) is: Open ground wire at the brake booster pressure sensor causing the signal to float to reference voltage
Typical repair costs for P0558 range from $60 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A stuck-high signal causes the ECM to perceive no brake booster vacuum at all times, which may trigger false brake assist warnings and disable vacuum management features. The vehicle's actual braking remains functional but safety monitoring is compromised.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0558 to identify the root cause.
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Quick Info
Category
Powertrain
System
Brake Assist / Brake Booster System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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