Code result
C0556
Brake Booster Pressure Sensor Performance
Moderate severity
What it means
The brake booster vacuum or pressure sensor signal does not respond plausibly to engine vacuum or electric booster activity.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Vacuum leak in booster line
highOne of the most commonly reported causes for this code — check this first.
Vacuum pump weak
mediumA plausible cause — test and verify before replacing parts.
Sensor element aged beyond calibration window
lowLess common, but worth ruling out after the more likely causes.
Related help
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