P0556 on Gmc Terrain
Brake Booster Pressure Sensor Circuit Range/Performance
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Gmc Terrain context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0556.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P0556 Means on Your Gmc Terrain
P0556 is a diagnostic trouble code indicating: Brake Booster Pressure Sensor Circuit Range/Performance. This code relates to the vehicle speed and idle control system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Gmc Terrain Owner Reports
Source: NHTSA Complaints Database
"I got off a highway exit ramp and with no warning my brakes were hard to press. There was no warning lights on my dash. The brakes take a lot of force to push for a stop. The warning light finally came on a day later with codes p0556 and u040171."
"This Saturday morning driving my family to Bradenton as I was coming off the hwy to my exit when I experienced a brake fail I thought, brakes got real hard and I couldn't stop the car on time like I wanted to, so I had to press the brakes pedal harder to come to a complete stop, three different plac"
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Gmc Terrain
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
-
1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
-
2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
-
3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.