The dealer has not been very familiar with the diesel option in this vehicle. Dealer has found nothing wrong with the engine in this regard. Now the car is out of warranty and will be very expensive to fix according to outside mechanics. The car is experiencing severe BLOW-BY When the oil filler cap is removed while the engine is running, the pressure coming out of the engine is very high. I…
2018 GMC Terrain engine problems
moderate 18 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
18
Recalls
0
Avg fix
$3,100
When does it fail?
Of the 18 engine complaints filed for the 2018 GMC Terrain, here's the actual mileage breakdown — failures cluster heaviest at 25,000-50,000 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
No new NHTSA engine complaint has been filed on this vehicle in over 3 years — the issue may be aging out of the active population.
What owners are reporting 4 most recent
Catalytic converter failed when driving damaging the engine. Vehicle undrivable and waited for repair at shop for over 90 days. Engine warning light keeps coming on with error code P1186 that the GMC dealer can not fix.
Beaverton GMC did repair work on my vehicle. During the inspection they said they found the radiator leaking from a number of spots and it needed replaced. It has never leaked and did not need replaced. Why did they do it? I as for the parts but they tossed them and would not give them to me.
The contact owns a 2018 GMC Terrain. The contact stated while driving at approximately 65 MPH, the check engine warning light illuminated, and the vehicle decelerated to 20 MPH. Additionally, the message "Service Emissions" was displayed. The vehicle was taken to the local dealer who diagnosed that the diesel particulate filter was faulty and needed to be replaced. The vehicle was not yet…
Had engine trouble with your 2018 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 engine problem on the 2018 GMC Terrain?
It's a documented issue but not catastrophic. 18 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Based on the 18 complaints filed, engine issues most often appear around 145,250 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 $3,100 for engine 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 engine?
No active recalls currently cover engine 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/2018/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.