Which Used Vehicles Draw the Most Brake Complaints? We Counted the NHTSA Data on GM's eBoost Cohort

Key facts

• Investigation: NHTSA's Office of Defects Investigation opened Engineering Analysis EA26006 on 2026-08-21, escalating from Preliminary Evaluation PE24011 (opened 2024-04-11 on 2023 Cadillac Lyriq loss-of-brake-assist reports).
• Scope: an estimated 1,164,820 vehicles across 12 GM nameplates plus 2 Honda-badged peers built with the eBoost electronic brake-boost system.
• NHTSA's own counts (Open Resume): 745 unique incidents (227 ODI complaints + 531 manufacturer reports), 22 crashes/fires, 5 injury incidents / 6 injuries, 0 fatalities.
• What we computed: 2,560 owner complaints across the cohort's EA model-year windows; 495 (19.3%) coded SERVICE BRAKES; 79 also carrying loss-of-braking language in the narrative.
• Mechanism (GM's account, under investigation): an alleged spindle fracture inside the eBoost unit. ABS, stability and traction control stay live until the vehicle fully stops, then drop, with the car limited to 70 kph (43 mph) and a "Service Brake System" warning.
• NHTSA's problem description (verbatim): "Failure of eBoost system causing loss of braking and steering assist functions."
• NHTSA's concern: some field reports allege loss of brake assist during a braking event, inconsistent with GM's stop-then-lose account.
• Status: no recall as of 2026-08-26. An EA is the last investigative step before NHTSA can compel one.
• Not in scope: the full-size Silverado 1500 and Sierra 1500 (different, non-eBoost booster). Only the midsize Colorado and Canyon are included.

Which used vehicles get the most brake complaints?

Within the eBoost cohort, the Chevrolet Traverse leads by a wide margin on the measure that depends least on our judgement: NHTSA's own component coding. More than half of everything Traverse owners complain about — 167 of 301 reports — is filed under SERVICE BRAKES. The GMC Acadia is close behind at 51.3%. No other cohort model exceeds 37%.

That framing matters because raw complaint counts mostly measure fleet size. The Honda Prologue has the largest raw complaint volume in the entire cohort at 960, more than three times the Traverse, yet only 6.4% of those are brake-coded. Composition, not volume, is what separates the models here. We used the same share-of-complaints approach for which used cars have the most backup camera failure complaints, and it sidesteps the missing sales denominator the same way.

Brake-complaint share — eBoost (EA26006) cohort

NHTSA ODI complaints, retrieved 2026-08-26. Composition, not a failure rate (no sales denominator). N = 2,560 cohort complaints; 495 coded SERVICE BRAKES; 79 also matching loss-of-braking narrative language.

The Cruise Origin robotaxi is in the EA population but returns no consumer complaints, and the Cadillac Celestiq has none on file — an ultra-low-volume car, so its zero reads as "no reports yet," not "no risk."

Does the pattern actually track the eBoost hardware?

Partly, and the honest answer is more mixed than the headline. The check most likely to break this story is whether brake complaints simply follow GM vehicles generally rather than the eBoost system specifically. So we pulled a contrast group of the two highest-volume GM trucks NHTSA explicitly excluded from EA26006 because they use a different booster: the Silverado 1500 and Sierra 1500. Despite far larger raw complaint totals (729 and 861), brake-coded complaints are only 4.8% and 3.6% of their own volume. Against the Traverse's 55.5%, that is more than a tenfold gap, and it is consistent with the eBoost hypothesis.

But the cohort does not hold together as a block. The Honda Prologue is an eBoost vehicle, and it is the single largest complaint generator in the cohort — yet at 6.4% brake-coded it sits barely above the non-eBoost Silverado, and below four other cohort models on the strict measure. The GMC Canyon (8.5%) is in the same position. If eBoost hardware alone drove the pattern, those two should not look like the contrast group. What the data actually supports is narrower than "eBoost vehicles get brake complaints": it is that two specific nameplates, the Traverse and the Acadia, are extreme outliers, and the cohort-wide story is not established. We flagged the same trap when asking whether owner complaints predict a recall — complaint patterns are a signal to read, not a verdict.

One more caveat that cuts against every number above: EA26006 was opened days before this analysis and drew heavy coverage. Recall and investigation publicity reliably lifts complaint filing for the named models, so some of the cohort's brake share is attention, not hardware.

By the numbers

• 2,560 — unique ODI complaints we processed across the 14 EA26006 nameplates, within each one's EA model-year window.
• 495 (19.3%) — of those coded by NHTSA to component SERVICE BRAKES.
• 79 — that also carry loss-of-braking language in the owner narrative.
• 55.5% and 51.3% — the Traverse's and Acadia's brake-coded share of their OWN complaints, the two highest in the cohort.
• 4.8% and 3.6% — the same measure for the non-eBoost Silverado 1500 and Sierra 1500 contrast group.
• 745 / 22 / 6 / 0 — unique incidents / crashes-fires / injuries / fatalities in NHTSA's own EA26006 tally.

What is the GM eBoost system, and which model years have it?

eBoost is GM's electronic (brake-by-wire) brake-boost system, and EA26006 covers specific model years of each nameplate, not the whole model run. GM attributes the failures to a spindle fracture inside the eBoost unit. On such a fracture, GM says the module sets a diagnostic trouble code on the Electronic Brake Control Module, sounds a chime, shows a "Service Brake System" message, and caps vehicle speed at 70 kph (43 mph). NHTSA upgraded PE24011 to a full Engineering Analysis specifically because some owners report losing assist during braking rather than after stopping.

The exact scope: 2023-2026 Cadillac Lyriq, Chevrolet Colorado and GMC Canyon; 2024-2026 Buick Enclave, Buick Envision, Chevrolet Blazer EV, Chevrolet Equinox EV, Chevrolet Traverse, Cruise Origin and GMC Acadia; 2025-2026 Cadillac Celestiq and Cadillac Optiq; plus 2024-2026 Acura ZDX and 2024-2026 Honda Prologue. If you are cross-shopping other GM models, our roundup of used car brands with the most recalls puts this probe in context — though an open investigation is not yet a recall.

Is this a recall, and what should an owner do now?

No recall has been issued. EA26006 is an Engineering Analysis, the final investigative step before NHTSA can request or compel a recall, and GM disputes the field-reported failure mode. An owner of an affected vehicle who sees a "Service Brake System" warning, a chime, or a sudden speed cap should stop safely and contact a GM (or Honda/Acura) dealer, and can monitor NHTSA's EA26006 record for any remedy. Because a VIN check does not decode investigation scope, pair it with NHTSA's own investigation page to confirm eBoost exposure. Distinct from this probe, we track parking-brake rollaway separately in our review of used SUV parking-brake rollaway complaints; those narratives are excluded here so the two do not overlap.

What a VIN check can and can't tell you here

A VIN check is useful for screening a specific used car's recall presence and its damage history, but it cannot map a VIN to this investigation or prove a brake fix. Use it alongside NHTSA's free tools and a dealer, not instead of them.

If you are looking at one of these models, the practical order is: start with NHTSA's free VIN recall lookup and the EA26006 record, then run a Zilocar VIN check to read that exact car's accident, salvage-auction, odometer, theft, ownership and sales-listing history alongside its recall screen. The listing and ownership history is the part free tools do not show, and it is what tells you whether the specific car in front of you has a red flag, independent of the model-wide complaint pattern above.

Method

Source file. NHTSA Office of Defects Investigation vehicle-owner complaints, retrieved 2026-08-26 from api.nhtsa.gov/complaints/complaintsByVehicle. This endpoint serves the same ODI complaint records NHTSA publishes as flat files at static.nhtsa.gov/odi/ffdd/cmpl/.

Universe (N). Every nameplate named in the EA26006 Open Resume, queried once per model year inside that nameplate's EA scope: Lyriq, Colorado and Canyon for 2023-2026; Enclave, Envision, Blazer EV, Equinox EV, Traverse, Acadia, ZDX and Prologue for 2024-2026; Celestiq and Optiq for 2025-2026. That returned 2,560 unique complaints. The Cruise Origin has no consumer complaint records and is excluded from the table.

Cleanup and dedup. Records were deduplicated on ODI number across model years and across trim-level nameplate entries, because NHTSA files some trims separately — COLORADO ZR2 BISON was folded into Colorado and CANYON AT4X AEV into Canyon. Model-year queries that return HTTP 400 mean no records exist for that year and were counted as zero, not as errors. One naming trap is load-bearing here: the Honda Prologue is filed under the model name PROLOGUE EV, not Prologue. Querying Prologue returns zero records, which would silently drop 960 complaints — 37.5% of the whole universe — and wrongly report the Prologue as having no complaints. Anyone reproducing this must use PROLOGUE EV.

Aggregation. Two independent measures, computed per nameplate:

1. Brake-coded share — the share of a model's own complaints for which NHTSA's components field contains SERVICE BRAKES. This uses only NHTSA's coding, with no judgement from us, and is the figure the headline rests on.
2. Strict loss-of-braking share — the subset of those that also match loss-of-braking language in the owner narrative (loss of brakes / lost brakes / loss of braking / brakes failed / brake failure / pedal to the floor / no brakes / hard pedal / loss of brake assist / could not stop / would not stop / reduced braking / brakes did not work), with parking-brake rollaway reports excluded so they do not double-count against our separate rollaway analysis.

Contrast group. The Chevrolet Silverado 1500 and GMC Sierra 1500 (2023-2026), both GM full-size trucks that NHTSA explicitly excluded from EA26006 because they use a different, non-eBoost booster. They are computed identically and reported alongside, not inside, the cohort totals.

Known limits. (1) There is no sales or registration denominator in ODI data, so every figure here is composition — the makeup of a model's complaint mix — and never a per-vehicle failure rate. (2) Complaints are unverified owner reports, not confirmed defects. (3) EA26006 opened on 2026-08-21 and was widely covered; investigation publicity raises complaint filing for the named models, so the cohort's brake share is inflated by an unknown amount relative to a quiet period. (4) Very low-volume models (Optiq, Envision, Celestiq) have denominators too small to rank meaningfully. (5) The counts move as NHTSA ingests new complaints; the frozen CSV below is the 2026-08-26 snapshot.

Related checks

• vehicle complaints by state
• which cars have the most fire complaints
• used cars with the most dashboard display problems

Sources

• NHTSA ODI Open Resume — Engineering Analysis EA26006 (GM eBoost electronic brake module failure; official counts and exact model-year scope)
• NHTSA ODI Open Resume — Preliminary Evaluation PE24011 (2023 Cadillac Lyriq; the evaluation EA26006 escalated from)
• NHTSA ODI complaints dataset — flat-file home (canonical source for the complaint records we processed)
• NHTSA ODI complaints API — complaintsByVehicle (the endpoint we pulled per nameplate x model year; reimplementable)
• Zilocar frozen CSV — brake-complaint share, eBoost EA26006 cohort plus the non-eBoost contrast group (our computed output, 2026-08-26)
• autoevolution — NHTSA expands GM eBoost brake-assist investigation to 1.1M vehicles (confirms no Silverado/Sierra)

Last verified: 2026-08-26