This informational bulletin instructs the tech when fuel/fluid is needed to be tested and where it can be sent for analysis.
full bulletin at NHTSA ↗2020 GMC Terrain brakes problems
severe Owners of the 2020 GMC Terrain have filed 54 NHTSA complaints about the brakes, typically surfacing around 108,000 miles at roughly $450 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See brakes across all vehicles →
Failure mileage
Complaints
54
Recalls
0
Avg fix
$450
| Model year | brakes complaints |
|---|---|
| 2016 Terrain | 4 |
| 2018 Terrain | 65 |
| 2019 Terrain | 42 |
| 2020 Terrain (this page) | 54 |
| 2021 Terrain | 6 |
4crashes
When does it fail?
Of the 54 brakes complaints filed for the 2020 GMC Terrain, here's the actual mileage breakdown — failures cluster heaviest at 150,000+ mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Owners have filed 54 brakes complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Among the 10 model years of GMC Terrain in our records for brakes problems, this one ranks #2 by owner-complaint volume.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering brakes on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This bulletin advises the dealers to maintain the vehicle stock on hand by doing a full inspection on the vehicles before being sold (prepping) to the customer.
full bulletin at NHTSA ↗This preliminary information discusses potential for a code C0010.5A to store in the brake controller which appears to be setting falsely or is induced by the customer.
full bulletin at NHTSA ↗This bulletin advises the dealers to maintain the vehicle stock on hand by doing a full inspection on the vehicles before being sold (prepping) to the customer.
full bulletin at NHTSA ↗This service bulletin provides diagnostic/repair information to correct customer concerns of a Crank No Start or Extended Crank, Malfunction Indicator Lamp (MIL) Illuminated or Possible Increased Brake Pedal Effort.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners report the brake vacuum pump in the 2020 GMC Terrain suddenly fails without warning while driving, leaving them unable to stop the vehicle. The brake pedal becomes brick-hard and immovable; some owners say they had to stand on the brakes or coast into a gas station, grass, or fence to avoid hitting other vehicles. The pump doesn't just fail—it shatters into fragments that contaminate the engine, scoring the camshaft and timing components.
Failures happen across a wide mileage range, from under 40,000 miles to over 160,000, with many occurring between 50,000 and 110,000 miles. There is no gradual warning. One moment brakes work, the next they don't, and a "Service Brake Assist" light only illuminates *after* the failure.
Repair costs run $1,000-$1,400 for pump replacement alone, but engine damage from metal contamination often pushes total repairs to $7,200-$11,000. Some owners discover metal fragments cannot be magnetically removed due to the pump's composite material. Dealership mechanics report having to disassemble and clean the entire engine.
GM has acknowledged the defect with a Technical Service Bulletin and issued a warranty program, but it's limited to certain manufacturing facilities—many owners' VINs are excluded despite having the identical part. Other GMC models got recalls for the same pump; the 2020 Terrain did not. One owner reported the brake booster failing five times in succession, each replacement failing again shortly after installation, indicating no fundamental fix has been applied.
Same GMC Terrain brakes reports on nearby years: 2018 · 2019
Failure modes owners describe
Brake Vacuum Pump Failure
The brake vacuum pump internally fractures or shatters, typically at the connection to the camshaft, and breaks apart into metal fragments. The pump loses its ability to supply vacuum pressure to the brake booster, resulting in complete or near-complete loss of brake assist and brake system failure. Pump failures have been documented across a wide mileage range from under 40,000 to over 160,000 miles.
When: Multiple owners report sudden failures with no prior warning or symptoms. Failures documented at mileages including: 17,361 miles, 40,000 miles, 53,000 miles, 56,456 miles (after prior replacement), 65,000-71,000 miles, 86,000 miles, 101,700-110,501 miles, and 156,000 miles. Some owners report repeated failures within 2-5 years of first failure.
Symptoms owners cite: Brake pedal becomes extremely stiff and hard to press, requiring excessive force or both feet to depress; Loss of brake assist, partial or complete brake system failure; Vehicle unable to stop or extended braking distance; Sudden appearance of 'Service Brake Assist' warning light on dash; Check engine light illumination; Engine operating at reduced power; Hearing ticking noise from engine compartment before failure; No advance warning in most cases; failures occur suddenly while driving
Codes mentioned: P0556, U0401, U040171
Repairs/costs cited: Repair typically involves replacement of the brake vacuum pump. Owner reports cite costs ranging from $1,000 to $1,400 for pump replacement alone. However, because the pump shatters and sends metal fragments into the engine, additional damage is common: camshaft damage, timing belt/chain damage, engine damage requiring full engine replacement (costs up to $11,000), and timing offset issues. Metal fragments must be manually removed from engine; magnetic removal is ineffective due to non-metal composite materials in pump construction. Some owners report the motor must be disassembled and cleaned. Repair costs have totaled $1,500-$11,000 depending on extent of engine damage from metal contamination.
Recalls/TSBs owners mention: GM has issued Technical Service Bulletin TSB 21-NA-107 describing the exact failure mode. GM has issued a warranty program/Special Coverage Adjustment (case referenced: N182202780) on this issue, but coverage is limited to specific VINs and certain manufacturing facilities—many owners report their vehicles are excluded from coverage despite having the same pump. Some owners had pump replaced under extended warranty (covering part cost or part and labor). GM developed an electric replacement pump for later production. Owners report GM acknowledges the issue exists but directs them to pay for diagnostics and file for 'Goodwill Repair,' which the company admits is unlikely to be approved. No full recall has been issued for 2020 Terrain model year, though recalls have been issued for other GMC model years with the same pump.
Brake Booster/Vacuum Booster Sensor Failure
The brake booster or vacuum booster sensor fails, reducing or eliminating brake assist. Owners report the booster sensor or booster component requires replacement, sometimes multiple times on the same vehicle. The failure is distinct from but related to the vacuum pump failure in that it directly impacts brake system function.
When: Documented at mileages including 37,435 miles, 57,087 miles (within months of pump replacement), 66,000 miles, and at or above 162,000 miles. One owner reported brake booster replacement five times between August 2024 and the date of complaint (same vehicle experiencing repeated failures).
Symptoms owners cite: Brake pedal is stiff and difficult to depress; Service Brake Assist warning light illumination; Check engine light; Loss of brake assist function; Reduced braking ability
Codes mentioned: P0556
Repairs/costs cited: Brake booster replacement costs cited: $1,441.63 (owner paid $100 out-of-pocket with extended warranty coverage). One owner had booster replaced five times, each time at Firestone initially under warranty, but the part continues to fail. Dealership ultimately refused to continue replacement, stating the vehicle is 'chewing up' the part and owner must return to dealership to resolve systemic issue.
Recalls/TSBs owners mention: Owners report booster sensor replacements covered under GM warranty, though some replacements fall outside warranty coverage. Repeated failures suggest GM has not addressed the underlying cause, and owners cite lack of effective solution to prevent recurrence.
Secondary Engine Damage from Vacuum Pump Contamination
When the vacuum pump shatters, metal fragments and debris enter the engine oil and combustion chambers, causing secondary damage to internal engine components. Damage includes camshaft scoring or fracturing, timing chain/belt misalignment, piston and rod damage, oil seal damage causing leaks, and in severe cases, mechanical failure requiring full engine replacement. Timing can become offset by up to 8% according to one owner's report.
When: Occurs immediately upon pump failure. Secondary damage severity depends on how long the vehicle is driven after pump failure and how much contamination is introduced. Owners report discovering timing offset and seal damage during subsequent repairs after initial pump replacement.
Symptoms owners cite: Engine operating in reduced power mode; Oil leak under vehicle; Grinding or abnormal engine noise after pump failure; Engine misfire or running issues that persist after pump replacement; Timing warning codes after initial repair
Repairs/costs cited: Engine cleaning and disassembly required to remove metal particles; magnetic removal ineffective. Full engine replacement costs reported at $7,200-$11,000. One owner reported timing offset of 8% requiring timing chain adjustment. Oil seal damage caused $1,800 repair. Camshaft replacement required in multiple cases as part of repair estimates.
Recalls/TSBs owners mention: No specific manufacturer response to secondary damage. GM directs owners to pay out-of-pocket or pursue Goodwill Repair claim, which owners report is unlikely to be approved.
Recurring Fuel System Issues Following Vacuum Pump Failure
One owner reported a cascade of fuel system failures following repeated vacuum pump failures and engine contamination. Issues included strong fuel odor in cabin and garage, fuel pump failure, fuel system cleaning and injector replacement, and temporary or recurring fuel smell.
When: Reported two years after first pump failure and second pump failure. Fuel pump failure occurred at approximately 100,000 miles.
Symptoms owners cite: Strong gasoline smell in vehicle cabin and garage; Fuel smell strong enough to prevent parking vehicle in garage; Risk of fire or explosion noted by owner; Fuel pump failure
Repairs/costs cited: Fuel pump replacement cost not specified by owner. Fuel injector replacement required. Fuel system cleaning performed but did not resolve issue permanently (smell returned after 2 weeks). Owner notes there is a separate recall for fuel pumps on this make, model, and year, but their VIN was not covered.
Recalls/TSBs owners mention: Fuel pump recall exists for this make, model, and year, but not for owner's specific VIN.
Synthesized from 54 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 6 most recent
No warning, the brake pedal went stiff as a board. No brakes could not stop doing 35 on a residential road. Had to coast to a stop in neutral.
The brake system failed. No warning. When the brakes failed, driver ran the car into a tree to stop instead of hitting pedestrians or other vehicles
Since August 2024, my brake booster has gone a total of five times each time with the notification on the dash service brake assist. And it just went again as of two days ago. I’ve brought it to Firestone where they have replaced it each time with a warranty on the part. I called them yesterday to tell them that it went again and they refused to fix it telling me that they got the part from the…
While driving my brakes failed. I was unable to stop my car, my brake pedal became very stiff and I could not stop my car. There were no warning signs or lights on indicating there were any issues with my car prior to this happening. I had to have my car towed to the dealer. The current estimate is for a vacuum pump failure resulting in camshaft damage. Both need to be replaced. I see other…
The contact owns a 2020 GMC Terrain. The contact stated that while driving up the driveway at approximately 10 MPH, the brake pedal was depressed but failed to function as intended. The contact used force to depress the brake pedal. When the vehicle came to a stop, there was an abnormal grinding sound coming from the front brakes. The contact stated that the message "Power Assist Brakes" was…
While driving on a main road at around 45mph the vacuum pump that supplies brake fluid to the brakes failed. The car was unable to be stopped and had it not been late in the night I could have crashed into other vehicles on the road or hit someone walking. There was not indication prior to the malfunction and was very sudden. This issue has been observed by the dealer as well as multiple other…
Had brakes trouble with your 2020 GMC Terrain?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the brakes problem on the 2020 GMC Terrain?
It's a meaningful issue. 54 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $450.
At what mileage does the brakes typically fail?
Across the 8 complaints that reported odometer mileage, most brakes failures cluster between 40,000 and 162,000 miles, with the median around 108,000. A quarter of owners report trouble before 40,000; a quarter make it past 162,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $450 for brakes repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to brakes?
No active recalls currently cover brakes issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2020/GMC/Terrain.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.