UK Reliability Directory

Mercedes-Benz B-Class (W246)

Production Years: 2011 - 20183 Documented Faults

The Mercedes-Benz B-Class (W246) is a practical, high-roof alternative to the A-Class, offering a vastly improved interior and better driving dynamics than its W245 predecessor. It is positioned as a premium family MPV, providing excellent visibility, easy ingress, and a spacious cabin for those who don't want an SUV. In the UK, it makes for very sensible, comfortable family transport with low running costs and reasonable insurance. However, it shares the same dual-clutch transmission (DCT) and diesel emissions risks as the W176 A-Class, making it best suited for mature drivers or families needing flexible premium space.

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Common Faults & Reliability

These are the most common documented problems for the Mercedes-Benz B-Class (W246), sorted by their typical impact and frequency.

7G-DCT Gearbox Judder

medium severity

The dual-clutch automatic can become hesitant or jerky if clutch wear is present or fluid changes have been skipped.

Est. repair cost:£400–£1,500

OM651 Diesel Timing Chain Tensioner Oil Leak

medium severity

The gasket on the timing chain tensioner is a frequent leak point. Oil loss can reduce tensioner pressure and lead to chain rattle and eventual stretch.

Est. repair cost:£200–£500

Water ingress in boot from rear air vent seals

medium severity

The rear air vent seals behind the bumper can fail, allowing water into the boot. This can damage the rear SAM electrical module, causing lighting and locking faults.

Est. repair cost:£100–£500

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