P0556 on Toyota: How to Diagnose & Fix
Brake Booster Pressure Sensor Circuit Range/Performance
1 Toyota model · 1 documented issue · 1 critical
P0556 on Toyota by model: symptoms, diagnosis and fix
NHTSA recall 21V890/Toyota 21TA09 covers certain non-hybrid 2018-2019 Camrys with the A25A-FKS engine, not Camry Hybrids or every vehicle in those model years. An affected vacuum-pump vane end cap can wear, break and lodge between the vane and housing, stopping the pump and suddenly reducing brake assist. The service brakes still function, but pedal effort increases and braking performance may be reduced, increasing crash risk. Toyota reports no expected advance warning before the condition occurs.
Common Symptoms
- Sudden increase in brake-pedal effort
- Brake-system warning indicators, warning chime or Low Braking Power message after assist is reduced
How to Fix
Check the VIN for open recall 21V890/Toyota 21TA09 and schedule an authorized Toyota dealer if open. The free campaign remedy is inspection of the vacuum pump and repair or replacement according to Toyota's recall procedure. If the brake pedal suddenly requires much more force, press firmly, increase following distance, reduce speed and stop in a safe location; warning lamps, a chime or a Low Braking Power message may appear only after assist is reduced.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Owner tips & cautions
- WarningToyota reports no expected advance warning before assist can be reduced. If pedal effort suddenly rises, press firmly, slow down and stop safely.
- TipCoverage is VIN-specific and excludes Camry Hybrids. An open 21V890/21TA09 campaign is repaired by Toyota free of charge.
Sources for this issue (3)
P0556 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0556 mean on a Toyota?
P0556 stands for "Brake Booster Pressure Sensor Circuit Range/Performance." The brake booster pressure sensor signal is present but out of the expected range or implausible relative to operating conditions. A range/performance fault. On Toyota it is documented across 1 model: Camry.
What are the most common causes of P0556?
The most common causes of P0556 are: Faulty brake booster pressure sensor, Vacuum leak at the booster or hose, Wiring resistance / poor connection, Failing vacuum source / pump, Faulty PCM input. The specific cause varies by vehicle.
How much does it cost to fix P0556 on a Toyota?
Repair costs vary widely with the root cause and Toyota model; each issue on this page carries its own estimate where one is published.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.