2018 GMC Sierra 1500: what breaks, and at what mileage

What breaks on the 2018 GMC Sierra 1500

Owners have reported 60 named failure modes on the 2018 GMC Sierra 1500, and the three most-reported carry 32% of everything filed, which is an unusually even spread for one model year.

Other powertrain problem leads with 77 reports, about 0.8 per 1,000 vehicles and with the middle half of reports between 14k to 47,500 miles.

Other brake problem follows with 33 reports, usually reported between 12k to 75,000 miles.

Other electrical problem follows with 27 reports, median 120,000 miles.

By system, the reports fall mostly into transmission (111), engine (67) and brakes (52).

Severity, and what it costs

Across the named modes, 13 mention a crash, 3 a fire and 5 an injury. Those are the words owners used in their own complaints, and NHTSA does not verify them, but they are the closest thing in this data to a measure of what a failure actually did.

The average severity weight across every report on this year is 4.08, where a stalled engine or a failed airbag weighs many times more than a rattling trim panel, and a figure this high means the reports are dominated by failures with safety consequences rather than annoyances. The weighting is set out in full on the methodology page.

What the top failures cost to put right, as editorial estimates for an independent US shop rather than figures from NHTSA: other powertrain problem at $400–$4,500, other brake problem at $300–$1,800, other electrical problem at $250–$2,000 and other engine problem at $300–$4,000. Dealer labour, a seized bolt or a part that is no longer made can push any of these past the top of its range.

47% of the reports on this year sit in the engine, transmission, drivetrain or cooling systems — the four where a repair bill is usually four figures.

How often, against how many were built

Scaled by an estimate of how many of these cars exist, the 2018 GMC Sierra 1500 draws about 4.7 per 1,000 vehicles, which puts it in the 84th percentile of complaint rates among 2018 vehicles we can rate.

That denominator is the weakest number on the page and it is fair to say so plainly. Rate per 1,000 uses a fleet-size estimate derived from recall paperwork for this exact model year. It is a lower bound.

The working figure is 90,966 vehicles. If the true number is twice that, every rate on this page is half what it says; the ranking against other 2018 vehicles, which is what the risk score uses, is far more robust than the rate itself.

Recalls on the 2018 model year

NHTSA has issued 7 recall campaigns covering the 2018 GMC Sierra 1500, affecting an estimated 108,677 vehicles. A recall is a different kind of evidence from a complaint: it is the regulator and the manufacturer agreeing that something has to be fixed, and the fix is free for as long as the car exists.

The campaigns cover air bags and air bags:side/window:curtain:inflator. Whether the work was actually done on the car in front of you is a question only the VIN can answer, and the manufacturer or NHTSA will answer it free.

Recalls also distort complaint counts. Publicity about a campaign reminds owners that complaining is possible, so reports for a recalled component often spike after the recall rather than before it.

Where 2018 sits in the model line

Severe risk for a 2018 — 86th riskiest of the 251 2018 vehicles we can rate. Because the ranking is against the same model year only, age cancels out of it.

Across the 30 model years of this car that carry enough reports to score, 1997 comes out best at 60 and 2019 worst at 81, with 2018 itself at 78.

If the model year is negotiable, 1997, 1999, 2012, 2013, 2010, 1998, 2001, 2014, 2008, 2007, 2009, 2000, 2005, 2015, 2011, 2002, 2016, 2003, 2004, 2017 and 2022 score lower than 2018 by a margin worth acting on. Same body, same engines, different luck — usually a supplier change or a mid-cycle fix, which the complaint data can show but never explain.

Within the 2014–2020 generation specifically, 2014 is the strongest year at 68 and 2019 the weakest at 81.

What to look at before buying one

The mileages below are where the first quarter of reports for each mode had already been filed, which makes them the point at which a fault is worth looking for rather than the point at which it happens: other steering problem from about 5k, other brake problem from about 12k, other powertrain problem from about 14k and other engine problem from about 24k.

On a 2018 GMC Sierra 1500 with more miles than that on it, the useful question to put to a seller or a mechanic is whether other steering problem has been dealt with, and if so with what parts and at whose expense. A car that has already had the repair is in a different position from one that has not.

None of this is a diagnosis. It is a list of what other owners of the same model year reported, ordered by when they reported it, which is a good place to point an inspection and a poor place to stop.

Where these figures stop being useful

424 owner reports; fleet size estimated from this year's own recall paperwork. Every count on this page is therefore a floor: it is the number of owners who went to the trouble of filing with a federal agency, which is a small and self-selected fraction of the owners who had the fault.

Of those 424 reports, 149 carried an odometer reading, so the mileages here describe 35% of the sample rather than all of it. Owners also round: readings pile up on multiples of ten thousand, which is why this site publishes "about 90,000 miles" and not "91,438".

Named failure modes come from matching phrases in the complaint text, so a badly worded complaint can land in the wrong bucket. The effect washes out across hundreds of reports and does not wash out across five.

And nothing here predicts what one car will do. These are other people's complaints, filed years apart, on cars maintained by strangers. Read the page as a map of where this model year has previously gone wrong, then have the specific car in front of you inspected.