Unclassified problem on the 2018 GMC Terrain
3 crashes 1 injury 4 of the 26 reports for this failure mention a crash, a fire, an injury or a death. Those are the owner's words on the complaint form, not a verified finding, and one report can mention more than one.
Only 15 reports for this mode came with an odometer reading, which is too few for percentiles to mean anything. The page is here because someone linked to it; treat the figures as anecdotes, and see the full report for this year instead.
When unclassified problem gets reported
Owners of the 2018 GMC Terrain report unclassified problem at a median of 5,000 miles. A quarter of the reports come in before 1,400 miles and a quarter after 15,000 miles, from 15 reports that carried an odometer reading.
It is the 48th most-reported problem on this model year.
The mileage distribution
The reported range runs from 200 miles at the tenth percentile to 55,000 miles at the ninetieth, a spread of 55,306 miles across the middle 80% of reports.
A window that narrow is the signature of a part that fails on its own schedule rather than on how the car is driven — which is usually a design or supplier problem rather than wear and tear.
80% of the dated reports were filed under 36,000 miles.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| 197 miles | 1,360 miles | 5,100 miles | 15,198 miles | 55,503 miles |
Read the 10th percentile as “one report in ten arrived this early”. Exact figures are shown in this table because it is the table of record; everywhere else on the site they are rounded to the precision the sample can carry.
What a percentile can and cannot tell you here
These five numbers describe the readings owners gave, in order. The median is the middle one: half the reports arrived below it. The 10th and 90th are the edges of the bulk of the distribution, and the distance between them is the part worth reading. A tight spread — say 70,000 to 95,000 miles — points at something that wears out on a schedule, and the schedule is knowable. A wide one, 20,000 to 190,000, points at a fault that hits some cars and never troubles others, which means the mileage on the listing in front of you tells you very little about your odds.
What these figures are not is a survival curve. Every reading here comes from a car whose owner filed a complaint, so the sample contains only failures: it cannot say what share of the fleet made it past 150,000 miles untouched, because those owners had nothing to report. Nor is the mileage the moment of failure — it is the odometer reading as recalled at the time of filing, which may be weeks later and is sometimes rounded to the nearest ten thousand by the person typing it.
Percentiles are shown at all only once 8 readings exist for the vehicle and mode. Below that the middle of a handful of numbers is noise wearing a decimal point, so the figures are withheld rather than dressed up.
What happens, and what it costs
Of these reports, 3 a crash and 1 an injury are mentioned. Owners write their own complaints and the agency does not verify them, so read this as what the reports say happened rather than as a confirmed count.
The same failure on other years
The same failure is reported on 12 model years of this car. It shows up earliest on the 2018, at a median of 5,000 miles, and latest on the 2012 at 70,000 miles.
By volume the 2011 carries the most reports, with 33; the 2018 has 26. A mode that appears across most years of a model is usually a design choice rather than a bad batch.
If one year stands out to the left, that is the year to avoid; if the whole line sits at a similar mileage, this is wear rather than a defect in one production run.
Tick median reported mileage Solid middle half of reports Faint 10th to 90th percentile Colour how bad the failure is when it happens
What owners wrote
Verbatim from NHTSA complaint narratives, trimmed for length. The mileage is the one the owner gave.
I pulled into our carport. It felt like the car just "sped up and went faster and faster." it hit the front of the car straight on. No airbags deployed nor did the front end collision stop happen.
Driving over a bridge over water,a loud explosion happened.at first I did not know what it was,until I heard wind blowing from the moon roof area.the glass on the roof exploded and sent glass down ward.luckily I had the moon roof shade closed or the glass would have came down on me.I nearly lost control. The weather was dry with a overcast sky. The traffic was very light.it was not possible for any foreign matter to hit the glass.I ammediately drove the vehicle to the gmc,where I purchased it.( dixie buick gmc).my vehicle only has 2040 miles on it.this was a saturday and the service dept. Was closed. Spoke to the sales manager,who said he never seen anything like this before. He gave me a loaner car to use. The service dept. Called on monday,and stated that the was no defect,and I or my insurance co, would have to pay. I called gmc customer support and they stated that they would do what the service dept. Said.so they will not cover it.finally today I called my insurance co. And looks like they also will not cover it.I'am still waiting for a final decision from state farm ins.my vehicle was traveling south on interstate 75 in…
Purchased a brand new gmc terrain. 12 days and 460 miles later the service engine soon light came on. Took it to dealership for a p050f. This is code for a leak in the booster. They did not repair anything, just checked for leak and reset engine light. As I read more, the problem affects the brakes ability to function properly increasing danger to driver. There is also defective stop/idle on the engine that no longer works. I was just driving down the road in town when it popped on. Gm and young's have refused to refund this defective vehicle.
Also reported on the 2018 GMC Terrain
Other brake problem
Other engine problem
Other powertrain problem
Other electrical problem
Other driver assistance problem
Parking brake failure
How far this goes
This page is kept out of search results because 26 reports is not enough to publish percentiles from. It stays reachable because somebody looking at this exact car would rather see the reports than be told there are none.
Complaints are voluntary, so 26 is a floor and not a count of affected cars. Mileages are typed in by owners and cluster on round numbers. And the mode itself is assigned by software reading the complaint text, which is reliable in bulk and fallible one report at a time.
Questions this page answers
At what mileage does unclassified problem happen on the 2018 GMC Terrain?
Across 15 owner reports that included an odometer reading, half were filed by 5,000 miles. A quarter were filed before 1,400 miles and a quarter after 15,000 miles. These are the mileages owners reported when they complained, not a prediction for any individual car.
How common is unclassified problem on the 2018 GMC Terrain?
26 reports have been filed with NHTSA, about 0.3 per 1,000 vehicles. Complaints are voluntary, so this is a floor rather than a count of affected cars.
What this is and is not. These are the mileages at which owners chose to complain to a federal agency, which is not the same as the mileage at which the part fails on every car. It skews toward failures that happened outside warranty, cost real money, or frightened someone. It is still the only public dataset that carries failure mileage at all, and the shape of a few hundred readings is informative even when a single one is not. Methodology · JSON · this failure on other cars
Source Owner complaints and recall records published by the US National Highway Traffic Safety Administration, model years 1996–2027 Figures rebuilt Published by AtWhatMileage How every figure is computed