What reliability score does the Mercedes-Benz B-Class get?

5.4 out of 10, scored from the 8 faults we document for this model and how severe each one is.

Is the 2019–2025 Mercedes-Benz B-Class reliable?

Scored from 8 documented faults · reviewed by the VehicleFaults Research Team

Quick answer

5.4/ 10

Mixed

On our documented-fault scoring the Mercedes-Benz B-Class rates 5.4 out of 10 · mixed. We hold 8 known faults for it and 1 are rated high severity, so the risk is real but contained. The weak points cluster around electrical, transmission and suspension. A well-serviced example with evidence for the big-ticket items is usually a safe buy; the score describes the model, not the specific car in front of you.

Verdict · Negotiate · budget for the known faults

What the score is built from

Critical: 0
High: 1
Medium: 6
Low: 1

Weak points cluster around electrical, transmission, suspension, brakes.

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The faults that decide it

Emissions (Diesel)High

Engine management light and non-start countdown

Typically appears: 30,000-50,000 miles
What to inspect: Turn the ignition on and scroll through the instrument cluster messages. Look for 'Refill AdBlue' warnings or a mileage countdown, which often indicates crystallized AdBlue injectors rather than an empty tank.
Typical repair: Injector set replacement & coding · £500–£1,600

TransmissionMedium

Dual clutch judder in slow traffic

Typically appears: 60,000+ miles
What to inspect: Pull away from cold repeatedly
Typical repair: DCT clutch pack / mechatronic work · £900–£3,200

ElectricalMedium

MBUX screen freezes and reboots

Typically appears: Age-related
What to inspect: Cycle every screen and voice function
Typical repair: Infotainment repair or software fix · £120–£1,200

BrakesMedium

Rear disc corrosion on low mileage cars

Typically appears: Age-related
What to inspect: Inspect rear discs for pitting
Typical repair: Brakes (discs, pads, caliper) · £200–£800

Engine (Petrol)Medium

Coolant loss and sweet smell under the bonnet

Typically appears: 40,000-60,000 miles
What to inspect: Shine a torch down the right side of the engine block (gearbox side) on 1.3L M282 engines. Look for pink or red crusty residue indicating a leaking plastic thermostat housing.
Typical repair: Head gasket / cooling system repair · £900–£2,600

Costs are indicative UK independent-garage bands for budgeting and negotiation · never a quote.

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What the score is built from

The faults that decide it

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Reliability of other Mercedes-Benz models