Quick Facts — Mercedes B-Class

Est. On UK Roads
70,000+
Years Made
2005–2023
Common Engines
1.3 petrol (B180/B200), 2.0 petrol (B250), 1.5 diesel (B180d), 2.0 diesel (B200d/B220d), Electric Drive (EV)

6 Most Common Mercedes B-Class Problems

These are the faults most frequently seen on the Mercedes B-Class by UK garages — ranked by how commonly they occur and what they cost to fix.

1
DPF Blockage (CDI Diesel)
High Priority
Diesel B-Class models on short urban family journeys develop DPF blockages frequently — a diesel MPV used for the school run is a high DPF risk.
💷 Typical repair cost: £150–£1,200
2
7G-DCT Dual Clutch Judder (W247)
High Priority
The 7G-DCT on W247 B-Class automatic models produces the same low-speed judder as across the Mercedes compact car range.
💷 Typical repair cost: £400–£2,000
3
AdBlue System (W247 CDI)
Watch
W247 CDI B-Class models require AdBlue. Running dry or sensor faults cause warnings.
💷 Typical repair cost: £10–£700
4
W246 7-Speed DCT Issues
Watch
The 7-speed DCT on W246 B-Class auto models can develop judder and mechatronic faults on higher mileage examples.
💷 Typical repair cost: £400–£2,000
5
Electric Drive Battery Degradation (B250e / Electric Drive)
Watch
The B-Class Electric Drive's battery degrades over time — real-world range reduces significantly on older examples.
💷 Typical repair cost: £2,000–£8,000
6
Sliding Rear Seat Mechanism Stiffness
Low Priority
The sliding rear seat mechanism can become stiff with age on older W246 models.
💷 Typical repair cost: £50–£200

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Mercedes B-Class — MOT Tips

DPF warning is an automatic MOT fail on diesel models. AdBlue warning is MOT-relevant on W247 CDI. 7G-DCT warning lights must be clear. Electric Drive high-voltage warnings must be clear on EV models. Being discontinued, factor in parts costs for out-of-warranty repairs.

Engine management light on before your MOT? It's an automatic fail. Run a Find Your Problem Now → to get the likely cause and repair cost before booking the test.

Mercedes B-Class Tyres

Most Mercedes B-Class models run 205/55 R16 or 225/45 R17 or 235/40 R18 depending on trim level and year. Always check the placard inside the driver's door for the exact size for your vehicle.

🔍 Not sure what's wrong? Check your symptoms & likely causes →

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Frequently Asked Questions

What is the most common problem with the Mercedes B-Class?

The most frequently reported issue on the Mercedes B-Class is DPF Blockage (CDI Diesel). Diesel B-Class models on short urban family journeys develop DPF blockages frequently — a diesel MPV used for the school run is a high DPF risk.

How many Mercedes B-Classs are on UK roads?

There are an estimated 70,000+ Mercedes B-Classs currently on UK roads.

What tyres does the Mercedes B-Class use?

Most Mercedes B-Class models run 205/55 R16 or 225/45 R17 or 235/40 R18 depending on trim level and year. Always check the placard inside the driver's door for the exact size for your vehicle.

Will a warning light fail my Mercedes B-Class's MOT?

DPF warning is an automatic MOT fail on diesel models. AdBlue warning is MOT-relevant on W247 CDI. 7G-DCT warning lights must be clear. Electric Drive high-voltage warnings must be clear on EV models. Being discontinued, factor in parts costs for out-of-warranty repairs.

Similar Issues on Other Models

Mercedes A-Class — shares the same AdBlue system problem Citroën C4 — shares the same DPF blockage problem

Summary

The B-Class is a very practical and comfortable used family car — particularly for buyers who value ease of entry and exit. The W247 is the better buy. The 1.3 petrol is the simplest and most reliable engine. Avoid diesel for city use. The 7G-DCT judder is manageable but worth knowing about. Being discontinued, the B-Class offers strong used value.

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Other Mercedes-Benz Models

Mercedes C-Class → Mercedes E-Class → Mercedes A-Class → Mercedes GLC →