All generations and engines together · 8,179 MOT tests in the 2025 data
Computed from DVSA MOT results, all of Great Britain, 2025. Nothing here is opinion.
Share of tests where each item was recorded. The dark tick is the class average across all tracked models; bars are scaled within each group.
The rows that judge the model rather than its keeper. 8,179 tests in this band.
Tyres, pads and stone chips say more about how the car was driven and maintained than about how it was built.
Owner folklore from forums and the motoring press. Most of it never shows up in an MOT, which is why this section exists at all.
The M260 1.3-litre turbo petrol fitted to GLB200 and GLB250 models can suffer exhaust valve seat and guide wear, causing a rough or noisy idle (owners describe a high-pitched rattle), misfires and a check engine light. It has shown up anywhere from under 30,000 miles to 70,000-plus. Mercedes-Benz extended the warranty on the affected exhaust valve assembly to 15 years/150,000 miles in North America after widespread complaints; no equivalent UK campaign has been confirmed, so an out-of-warranty full cylinder head replacement is a genuinely expensive repair.
On mild-hybrid EQ Boost cars, a software communication error during 48V lithium-ion battery reinitialisation can trip the warning light for no real reason. Mercedes ran a free service campaign (numbered 2025100004 on paperwork owners have shared) on 2024-2025 GLB, GLA and CLA models, applied during a routine service. It doesn't affect the ordinary non-hybrid petrol or diesel GLBs.
Owners report an intermittent squeak from the front end on slow, tight turns that dealers have struggled to reproduce or pin down, sitting alongside a general complaint that the ride is firm over sharp bumps and potholes, worse on AMG Line cars with bigger wheels and lower-profile tyres. That matches the measured picture: suspension is the standout MOT fault for large SUVs generally, and the GLB's firmer, harder-worked front end fits the pattern, even though the forum noise itself has never been traced to one specific part.
A recurring forum topic: owners get a low-voltage warning through the Mercedes Me app after the car sits for a couple of weeks, and some report the battery still isn't fully charged even after a decent run. Opinion is split between "normal for any modern car loaded with standby electronics, use a maintainer" and a genuine charging-system shortfall; a few owners had the battery replaced under goodwill rather than wait for a full failure. Worth knowing if you're buying one as a second car that won't be driven daily.
Built from the two sections above.
Same segment (Family & large SUVs), best MOT record first. Compare before you shortlist.