P0556 on Chevrolet: How to Diagnose & Fix
Brake Booster Pressure Sensor Circuit Range/Performance
3 Chevrolet models · 4 documented issues · 4 critical · $400-$1,800 repair
P0556 on Chevrolet by model: symptoms, diagnosis and fix
The T1 generation Silverado can experience brake assist malfunctions, causing a hard brake pedal, longer stopping distances, and warning lights. The electric brake booster or its sensors may be the cause.
Common Symptoms
- Hard brake pedal
- Service Brake Assist message
- Longer stopping distance
- Brake warning light
- ABS/traction lights on
How to Fix
Have dealer diagnose specific brake booster component failure. Brake booster assembly replacement typically required. Check for GM service campaigns or extended warranty coverage. Do not drive with reduced brake assist.
Sources for this issue (1)
The engine-driven brake vacuum pump on 2014-2018 Silverado 1500 trucks (5.3L and 6.2L V8) can lose vacuum output over time as oil sludge and debris are trapped by the pump's oil inlet filter screen. As vacuum drops, power brake assist decreases, producing a hard brake pedal, increased pedal effort, and longer stopping distances, most noticeably at low speed (parking lots, slowing for crosswalks). GM recalled roughly 3.4 million trucks and SUVs for this condition under NHTSA campaign 19V645000 (GM recall N192268490), and NHTSA's underlying investigation was closed after the recall.
Common Symptoms
- Hard brake pedal / increased braking effort
- Longer stopping distances, especially at low speed
- Service brake assist or ABS warning
- Reduced power brake assist when maneuvering slowly
How to Fix
Under the recall, dealers reprogram the Electronic Brake Control Module (EBCM) software to better detect low vacuum and compensate via the ABS/stability system; affected owners should confirm the recall remedy has been applied via VIN at NHTSA.gov. Out-of-recall vehicles experiencing a hard pedal should have the vacuum pump tested and replaced if output is low, and the oil change interval kept current to limit sludge.
Sources for this issue (1)
Third-generation Equinox (2018-2022) uses a camshaft-driven mechanical vacuum pump mounted at the rear of the cylinder head to supply the brake booster (the turbo intake is pressurized, so there is no manifold vacuum). This pump can seize and its drive gear break, suddenly eliminating brake assist — the pedal becomes 'hard as a rock' with greatly increased stopping distances. In severe cases the pump shatters and sends metal debris into the engine, causing catastrophic internal damage. NHTSA has over 300 complaints; a related GM recall (19V645000) reprogrammed the brake control module on other models but excluded the Equinox/Terrain, and a February 2026 class action (Thieme v. General Motors) targets 2018-2022 Equinox/Terrain.
Common Symptoms
- Sudden hard/stiff brake pedal
- Greatly increased stopping distance / loss of power assist
- Long crank or crank-no-start
- Noise from rear of engine before failure
How to Fix
If the brake pedal suddenly goes hard, stop driving and tow the vehicle — continued driving risks a crash and possible engine destruction. Replace the failed vacuum pump (and brake booster if damaged); inspect for metal debris in the engine if the pump came apart. Check VIN for any applicable recall/special coverage and document the complaint with NHTSA.
Sources for this issue (1)
2015-2018 Chevrolet Suburbans are covered by GM safety recall 19V645000. GM determined the vacuum produced by the vacuum pump may decrease over time, and the brake booster depends on that vacuum to do most of the work of applying the brakes. On a vehicle as heavy as the Suburban, losing assist matters: NHTSA states that as the vacuum level drops, braking effort increases and the distance required to stop the vehicle extends, raising crash risk. The condition builds gradually, so it is easy to adapt to a stiffening pedal without recognizing it as a defect. The recall's 3,456,719 units affected is a campaign-wide total covering all the GM trucks and SUVs named in it.
Common Symptoms
- Increased brake pedal effort
- Longer stopping distances
- Weakening power brake assist over time
How to Fix
The fix is free at a Chevrolet dealer and takes the form of a software update - the dealer reprograms the Electronic Brake Control Module. GM began owner notification October 8, 2019; the internal campaign number is N192268490. Enter your Suburban's VIN at nhtsa.gov/recalls to confirm whether this recall is still open, then contact Chevrolet customer service at 1-800-630-2438 or your local dealer to have the reprogramming performed.
Sources for this issue (1)
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 Chevrolet?
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 Chevrolet it is documented across 3 models: Silverado 1500, Equinox, Suburban.
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 Chevrolet?
Published repair estimates on Chevrolet range from $400 to $1,800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0556 on a different make?
View P0556 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.