P0555
UniversalBrake Booster Pressure Sensor Circuit
The brake booster pressure sensor reports pressure in the brake booster to the vehicle’s control system. P0555 means a fault was detected in the sensor circuit; it does not prove the sensor itself has failed. Depending on the vehicle and the fault, brake assist may be affected or there may be no noticeable change.
⚠️ Before You Begin (Safety First)
Brakes may require more effort if brake assist is reduced. If the pedal becomes unusually hard, braking changes, or a brake warning appears, stop somewhere safe and arrange professional inspection rather than continuing to drive. Do not disconnect or bypass brake-system components.
Common Symptoms
- No noticeable symptoms; the fault may be detected before the driver notices a change.
- A brake warning or check-engine light may appear, depending on the vehicle’s monitoring and warning strategy.
- The brake pedal may feel harder or require more effort if brake assist is reduced.
- Brake assist or pedal feel may be inconsistent if the reported pressure does not match actual booster pressure.
Common Causes
- A fault inside the brake booster pressure sensor.
- Damaged, loose, or corroded sensor connector or wiring.
- A problem with the sensor circuit’s power, ground, or signal path.
- A pressure or booster-system problem that causes an implausible sensor reading.
Diagnostic Steps
- Note any brake warning lights or changes in pedal feel; if braking has changed or the pedal is unusually hard, stop driving and seek professional help.
- With the vehicle safely parked and switched off, visually check accessible sensor wiring and connectors for looseness, damage, or corrosion. Do not unplug components unless the vehicle’s service information says it is safe.
- Check for other diagnostic codes and record them before clearing anything; related codes can help distinguish a circuit issue from a broader brake-assist problem.
- If the warning remains, have a qualified technician test the sensor circuit and pressure readings using vehicle-specific service information.
When to Call a Professional
Use service information for the exact vehicle to check the circuit and sensor. A technician can inspect connector and wiring condition, verify the sensor’s power, ground, and signal as applicable, and compare scan data with an appropriate pressure measurement. Diagnose the circuit before replacing parts.
Compare component listings
Confirm diagnosis and vehicle fitment before buying. A listing does not prove that a part needs replacement. We may earn a commission from qualifying purchases.
Commonly Asked Questions
Does P0555 mean the brake booster pressure sensor must be replaced?
No. The code identifies a detected circuit fault, not a confirmed failed part. Wiring, connectors, circuit supply or ground, and pressure-related issues should also be considered.
Can I keep driving with P0555?
If pedal feel or braking has changed, or a brake warning appears, stop somewhere safe and arrange inspection. If there are no symptoms, have the fault checked promptly because brake assist may be affected.
Can P0555 cause a hard brake pedal?
A hard pedal can occur if brake assist is reduced, but the code alone does not establish that this is happening. A technician should check actual assist and the sensor circuit.
Can the code appear if the sensor is working?
Yes. A connector, wiring, or other circuit problem can prevent the control system from receiving a valid sensor signal. Vehicle-specific testing is needed to identify the cause.
Browse Available Code Guides
Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.