The contact owns a 2020 GMC Terrain. The contact stated that while at a stop, there was an abnormal burning odor coming from the vehicle, with the service brake assist message displayed. The brake pedal became firm, and the contact used excessive force to stop the vehicle. The contact pulled into a gas station and restarted the vehicle while the check engine light was illuminated. Despite the…
2020 GMC Terrain powertrain problems
moderate 23 complaints filed with NHTSA · avg repair $2,500 · see powertrain across all vehicles →
Complaints
23
Recalls
0
Avg fix
$2,500
When does it fail?
Of the 23 powertrain complaints filed for the 2020 GMC Terrain, here's the actual mileage breakdown — failures cluster heaviest at 50,000-75,000 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.
The failure pattern owners describe
Buyer takeaway: A 2020 GMC Terrain powertrain cluster shows recurring safety issues—unresponsive acceleration from stops with no warning lights, unexpected transmission neutral shifts, stalling, and brake failures—many occurring without diagnostic codes or factory recalls despite similar issues being recalled on other model years. Excessive oil consumption requiring engine replacement and turbo failures also documented at relatively low mileage.
Owners report a cluster of powertrain failures on 2020 Terrain models that create acute safety hazards. The most consistent issue is unresponsive acceleration: vehicle takes 4-15 seconds to accelerate from a full stop despite pedal pressed to the floor, then lurches forward unexpectedly. This happens repeatedly at startup after the vehicle sits, especially at intersections and traffic merges. Dealerships and independent mechanics run diagnostics and find nothing; no codes illuminate.
Equally dangerous: transmission shifts into neutral mid-drive, stalling the vehicle. One owner reported the dealership found missing bolts on the transmission's START/STOP accumulator cap. A separate complaint documents that turbo failures leave vehicles stuck at under 20 mph in 65 mph zones.
Brake system failures also appear—complete brake failure requiring excessive pedal force or loss of power while turning. Some failures coincide with vacuum pump damage; GM issued a 10-year recall on vacuum pumps for other model years but 2020 Terrain owners report being excluded despite identical symptoms.
Engine issues include alarming oil consumption (full supply burned in one hour), requiring engine rebuild at $10,700, and multiple instances where dealership-installed replacement engines failed within weeks. Owners note no low-oil warning ever illuminated before catastrophic damage occurred.
Transmission shifts grinding, transmission slipping, and acceleration wobble at low mileage also documented. No warning lights precede most of these failures.
Same GMC Terrain powertrain reports on nearby years: 2017 · 2018 · 2019
Failure modes owners describe
Loss of power / No acceleration response on startup
Vehicle fails to accelerate normally when taking off from a stop or after startup. Drivers depress accelerator but vehicle moves very slowly or not at all for 4-15 seconds before power returns unexpectedly. No warning lights or diagnostic codes present.
When: Upon startup after vehicle has sat for hours or days; sporadic, unpredictable
Symptoms owners cite: Slow acceleration from full stop with pedal to the floor; Vehicle lurches forward after 4-15 second delay; No warning lights illuminated; No diagnostic fault codes; Occurs 4-5 consecutive times before vehicle 'warms up' and runs normally
Repairs/costs cited: Dealership diagnostics and independent mechanics unable to diagnose; no fault codes retrieved despite issue occurring during mechanic test drive
Transmission shifts to neutral unexpectedly / Loss of motive power
While driving normally (turning, accelerating), transmission suddenly shifts into neutral, causing loss of power and stalling. Vehicle fails to respond to Drive or Reverse commands temporarily. One case involved missing bolts on START/STOP accumulator in transmission cap.
When: While turning or driving at normal speeds; approximately 94,000 miles in one case
Symptoms owners cite: Transmission shifts to neutral during normal driving; Brief loss of motive power and stalling; Vehicle will not shift to Drive or Reverse after incident; Issue resolves temporarily after opening and closing door or restarting; Transmission fluid leaking in separate incident; Constant transmission slipping; Check engine light intermittently illuminated
Codes mentioned: Unknown code (one case did not specify)
Repairs/costs cited: Diagnosis at dealership found missing bolts on START/STOP accumulator cap; repair cost cited as prohibitive; independent mechanics confirmed transmission failure; vehicle not repaired
Recalls/TSBs owners mention: Manufacturer made aware; no recall or service campaign mentioned
Engine stalling / No-start condition
Engine stalls during normal driving or fails to start after parking. Stalling occurs frequently at stop signs, red lights, and with auto stop/start feature engaged. Vehicle will not start for extended period, producing only cranking sounds.
When: At stop signs and red lights; after parking for 2-3 hours; unpredictable
Symptoms owners cite: Unintended stalling at stops and intersections; Vehicle goes into park unexpectedly while driving; Failure to start after parking, requiring 30 minutes of attempts; Screeching metal sounds during cranking attempts; Vehicle shuts off by itself while running and stationary; Stalling occurs frequently with auto stop/start feature on; No warning lights prior to failure; Engine cranks but will not turn over
Codes mentioned: Yellow engine light illuminated (after stall/no-start event)
Repairs/costs cited: OnStar diagnostics run while parked showed no codes; no repairs documented in narratives
Recalls/TSBs owners mention: Auto stop/start feature cannot be disabled per owner account; lifetime warranty offered but service denied or delayed
Excessive oil consumption / Engine damage
Engine burns through oil at alarming rate, consuming a full supply within one hour of operation. This causes damage to coils, spark plugs, and pistons. Multiple cylinder misfires and poor performance result. Diagnosis indicates internal piston damage and internal oil leak requiring full engine replacement.
When: Recurring throughout vehicle ownership; one case at 83,000 miles
Symptoms owners cite: Oil level drops to empty within one hour of driving; Coils and spark plugs fail within 24 hours of oil burn episode; Cylinder misfires; Poor vehicle performance; Transmission stall related to low oil; Black soot covering entire engine; Oil leak underneath hood
Codes mentioned: P06DD, P0324, Check Engine Light illuminated after engine damage
Repairs/costs cited: Full engine rebuild or replacement required; dealership estimate $10,700 for engine rebuild; no low oil warning light displayed before damage occurred despite regular oil changes; another case required multiple engine replacements (three engines in one month)
Recalls/TSBs owners mention: No recall issued for excessive oil consumption defect; manufacturer not responsive in narratives
Acceleration wobble / Front-end shaking during acceleration
Vehicle shakes or wobbles in front end when accelerating uphill or turning while applying throttle. Tire slipping and clicking/whining noises from front. Issue persists even after tire replacement.
When: From one month after purchase onward; at 6,000 miles and 104,000 miles
Symptoms owners cite: Wobble in front end when accelerating uphill; Shaking when turning while on the gas; Tire slipping and clicking/whining from front of vehicle; Issue persists after tire replacement by dealership; Vehicle shakes every time driven; No warning lights illuminated
Repairs/costs cited: Dealership changed front tires but issue persisted; dealership could not find anything wrong; no repair performed
Recalls/TSBs owners mention: Dealership reported GMC was requesting dealer information about problem; customers told to wait for GMC solution; no fix implemented
Reduced power mode / Limp mode activation
Vehicle enters reduced power or limp mode unexpectedly, limiting acceleration and performance. In some cases vehicle stalls when in limp mode. Multiple complaints linked to intercooler problems and vacuum pump failures.
When: While driving; recurrent within 10 months after intercooler replacement in one case
Symptoms owners cite: Vehicle shifts into reduced speed/reduced power mode; Vehicle stalls while in limp mode (safety hazard); Multiple engine lights come on; Brakes stop working when reduced power engages; Timing chain breaks in conjunction with vacuum pump failure
Repairs/costs cited: Intercooler replacement performed but defect recurred within 10 months; vacuum pump failure caused timing chain damage requiring $3,000+ in repairs; parts removed from engine required recovery
Recalls/TSBs owners mention: Recalls exist for vacuum pump and timing chain defect on other model years (2021, 2022) but 2020 models not included despite same symptoms; GM warranty extension on vacuum pump (10 years/150k miles) not applied to 2020 models; manufacturer stated nothing could be done without recall
Turbo failure / Overboosting
Turbocharger fails or overboosts, causing loss of power and inability to accelerate or shift gears. Multiple instances of overboosting with excessive heat requiring temporary repairs (thermal tape).
When: At intersection/entering interstate; recurring overboosting issue within short timeframe
Symptoms owners cite: Sudden loss of ability to accelerate; Vehicle stuck at low speed (under 20 mph in 65 mph zone); Failure to shift gears properly; No warning lights before failure; Turbo overheats when overboosting; Recurring overboosting issue (multiple shop visits)
Repairs/costs cited: Turbo overboosting repaired four times with thermal tape applied as temporary fix; concerns raised about fire risk from electrical/thermal issue
Recalls/TSBs owners mention: No recall or extended warranty mentioned
Brake system failure / Hard brake pedal / Loss of brake assist
Brakes become difficult to press or stop functioning entirely while driving. Brake booster sensor circuit failure reported. Abnormal burning odor accompanies failure. Service brake assist message displayed.
When: While driving and making turns; at stop signs and intersections
Symptoms owners cite: Brakes hard to press, requiring excessive force; Complete brake failure while trying to make turn; Brake pedal becomes firm; Abnormal burning odor from vehicle; 'Service brake assist' message displayed; Check engine light illuminated during brake failure
Codes mentioned: Brake Booster Sensor Circuit (per AutoZone assessment)
Repairs/costs cited: Vacuum pump failure caused brake system issues; brake booster sensor circuit implicated; excessive force required to stop vehicle; brake diagnostics not completed in narratives
Recalls/TSBs owners mention: NHTSA Campaign 20V668000 (Powertrain) identified in one narrative but vehicle not on recall list; vacuum pump warranty extension (10 years/150k miles) not applied to all 2020 Terrain models
Sunroof drainage failure / Water intrusion / Electrical damage
Sunroof fails to drain properly after rain, causing water to flood interior. Backseat and rear wheel well flooded. Water ingress damages electrical components and sunroof mechanism.
When: After heavy rain; electrical failure occurred following water intrusion
Symptoms owners cite: Backseat flooded after heavy rain; Rear wheel well filled with water; Sunroof mechanism electrical failure; Risk of damage to other electrical elements
Repairs/costs cited: Dealership to assess; issue noted as known problem by owner research
Premature starter motor failure
Starter motor fails at 83,000 miles, well before typical service life. Associated with broader electrical system issues requiring $5,000+ in repairs.
When: At 83,000 miles
Symptoms owners cite: Starter motor failure
Repairs/costs cited: Starter replacement part of $5,000+ repair bill including water pump and drive belt; starter should last up to 100k miles per owner
Transmission gear shifting issues / Hard shifting
Vehicle fails to shift gears properly or smoothly. Hard shifts, grinding, and inability to engage Drive or Reverse reported.
When: While accelerating; intermittent throughout ownership
Symptoms owners cite: Vehicle will not shift to Drive or Reverse; Hard or delayed shifting; Grinding/skipping feeling while driving; Transmission slipping; Inability to accelerate after shift attempt
Repairs/costs cited: No repairs documented; dealership unable to recreate issue; extended warranty purchased but no service action taken
Synthesized from 23 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 3 most recent
The contact owns a 2020 GMC Terrain. The contact stated that while driving 35 MPH and depressing the accelerator pedal while driving uphill or making a left or right turn, the tires were skipping, and there was a clicking and whining sound coming from the front of the vehicle. There was no warning light illuminated. The contact stated that a friend test-drove the vehicle and informed that the…
The intercooler has been a document problem on GMC Terrains for awhile now. I had my intercooler replaced and now less than 10 months it is having the same problem. The vehicle will go into reduced power mode which would be a safety hazard because it will also stall sometimes when it is having performance issues. That could lead to someone colliding into me if it suddenly stops when someone is…
Had powertrain 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 powertrain problem on the 2020 GMC Terrain?
It's a documented issue but not catastrophic. 23 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain typically fail?
Based on the 23 complaints filed, powertrain issues most often appear around 65,000 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $2,500 for powertrain 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 powertrain?
No active recalls currently cover powertrain 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.