P0556 on GMC TERRAIN — Brake Booster Pressure Sensor Circuit Range/Performance

Q: "What does P0556 mean on a GMC TERRAIN?"

"P0556 indicates: Brake Booster Pressure Sensor Circuit Range/Performance. This is a vehicle speed and idle control code. 2 GMC TERRAIN owners have reported this to NHTSA."

Q: "What are the most common causes of P0556 on GMC TERRAIN?"

"Based on 2 NHTSA reports, the most commonly cited components are: Service Brakes. These percentages are based on the component field in owner complaints."

Q: "Is P0556 serious on my GMC TERRAIN?"

"Of 2 NHTSA reports for this code on GMC TERRAIN, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic."

Q: "What should I do if my GMC TERRAIN shows P0556?"

"1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare."

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.

2 GMC TERRAIN owners have reported this issue to NHTSA across model years 2020. Most reports come from the 2020 model year. The most commonly reported component is Service Brakes (100.0% of reports).

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."

— 2020 GMC TERRAIN owner · SERVICE BRAKES · Filed 06/10/2025

"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"

— 2020 GMC TERRAIN owner · SERVICE BRAKES · Filed 02/02/2024

All reports filed by vehicle owners directly with the U.S. Department of Transportation.

📊 Complaint Trend by Model Year

2

'20

Common Causes on GMC TERRAIN

Based on NHTSA complaint component analysis for this vehicle.

SERVICE BRAKES 100%

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.

Frequently Asked Questions

What does P0556 mean on a GMC TERRAIN? ▾

P0556 indicates: Brake Booster Pressure Sensor Circuit Range/Performance. This is a vehicle speed and idle control code. 2 GMC TERRAIN owners have reported this to NHTSA.

What are the most common causes of P0556 on GMC TERRAIN? ▾

Based on 2 NHTSA reports, the most commonly cited components are: Service Brakes. These percentages are based on the component field in owner complaints.

Is P0556 serious on my GMC TERRAIN? ▾

Of 2 NHTSA reports for this code on GMC TERRAIN, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic.

What should I do if my GMC TERRAIN shows P0556? ▾

1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare.

P0556 on Other Vehicles

CHEVROLET MALIBU

6 reports

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