Mercedes-Benz B-Class common problems & fixes (W246 2012–2018, W247 2019 onward)

Written by the C4R team from DVSA data and owner reports. Fact-checked 2026-10-08.

30-second verdict

The B-Class is a roomy five-seat alternative to a compact SUV. The W246 needs careful checks for diesel particulate-filter trouble and a weak battery that disables stop/start. On the W247, test every fitted function and make sure the seven-speed automatic behaves cleanly at low speed. Service history, a cold test drive and a registration-specific recall check matter more than the badge on the boot.

Generations at a glance

Generation	UK years	Main engines	Gearboxes
W246	2012–2018 (facelift 2014; a few registered later)	1.6 and 2.0 turbo petrol; 1.5, 1.8 and 2.1 diesel; rare Electric Drive	6-speed manual, 7G-DCT wet dual-clutch automatic
W247	2019 onward (facelift 2022/23)	1.3 and 2.0 petrol; 1.5 and 2.0 diesel; B250e plug-in hybrid	7-speed and 8-speed dual-clutch automatic

Engine availability changed during both generations. A B180 or B200 badge does not identify one engine throughout the whole period, so check the VIN, engine code and original specification before ordering parts.

Known issues

1. Diesel particulate filter clogging — Reported by owners and used-car specialists

What you notice: a DPF warning, loss of performance or reduced-power running.
Which cars: W246 and W247 diesels, particularly cars used mainly for short journeys or left standing for long periods.
Why: the exhaust does not stay hot for long enough to complete regular filter regeneration.
Fix: diagnose the loading level and the reason regeneration has not completed. Do not assume that a fast run will safely clear a warning that is already on.
Check when buying: favour a diesel with evidence of regular longer journeys. Walk away from an unexplained warning light until a proper diagnostic check has been completed.

2. ECO stop/start unavailable — Reported by owners and workshop technicians

What you notice: the ECO symbol remains unavailable, the engine does not stop at a standstill, or it fails to restart after an ECO stop. Fault code B21059A can accompany low starter-battery capacity.
Which cars: chiefly W246 models equipped with stop/start.
Why: a low state of charge or an ageing starter battery can prevent the system from operating.
Fix: identify the fitted battery type, charge and test it, then replace it with the correct specification if it fails. Battery replacement and any required vehicle coding should be handled by a suitably equipped garage.
Check when buying: test stop/start after a proper drive, but remember that temperature, electrical load and other normal operating conditions can also inhibit it.

3. Seven-speed DCT hesitation — Reported in independent road tests

What you notice: hesitation when pulling away or a delay before the gearbox kicks down.
Which cars: W247 petrol models using the seven-speed dual-clutch transmission, including B180 and B200 versions.
Why: road tests describe this as a driveability weakness; they do not establish that hesitation alone proves a mechanical failure.
Fix: pronounced judder, delayed engagement, a warning message or limp mode needs diagnosis. Do not authorise gearbox work from the road-test symptom alone.
Check when buying: compare cold and warm behaviour, creep in traffic, reverse into a space and accelerate from a junction. The response should be predictable and free from warning messages.

Recalls

The table below is a selection of the more relevant W246 and W247 campaigns in the DVSA Vehicle Safety Branch recalls data. The build windows are exactly those recorded by DVSA. Several campaigns cover other Mercedes models as well, and a car inside a date window is not automatically affected. Check the registration on the GOV.UK recall checker and ask for evidence that outstanding work has been completed.

DVSA ref	Launched	B-Class build window	What it covers
R/2013/069	25 July 2013	14 January 2012 – 18 May 2012	The Easy Vario rear back-rest lock might fail under extreme loading in a rear impact; the lock is checked and replaced if required.
R/2015/099	14 July 2015	1 September 2011 – 30 June 2013	A driveshaft could separate from its outer-joint hub; the retaining parts and outboard boots are replaced.
R/2015/210	19 November 2015	16 July 2015 – 11 September 2015	An exhaust camshaft made outside specification could break and cause sudden loss of drive; the camshaft is replaced.
R/2015/259	21 January 2016	28 October 2015 – 19 November 2015	High-pressure fuel lines could crack and leak, creating a fire risk near an ignition source; the lines are replaced.
R/2017/096	20 June 2017	1 February 2014 – 28 February 2017	Repeated attempts to start a seized engine could overheat the starting-current limiter; an additional fuse is fitted.
R/2017/177	20 June 2017	1 August 2016 – 31 March 2017	The front passenger airbag igniter might not deploy the airbag fully; the airbag assembly is replaced.
R/2017/179	20 June 2017	1 April 2011 – 30 April 2013	The brake-booster vacuum-line connection might fail, increasing the pedal effort needed after several applications; the vacuum line is replaced.
R/2018/098	11 May 2018	1 November 2011 – 31 July 2017	Insufficient grounding and a failed steering-column clock spring could trigger the driver's airbag unexpectedly; an additional grounding contact is fitted.
R/2019/097	1 April 2019	1 August 2018 – 31 December 2018	Driver-airbag locknuts might not be tight enough; the driver airbag is replaced.
R/2019/217	30 July 2019	1 July 2018 – 28 February 2019	The transmission might temporarily refuse Drive or Reverse; its control-unit software is updated.
R/2020/262	12 October 2020	21 October 2019 – 26 June 2020	The turbocharger oil-supply line might leak; it is checked and replaced if necessary.
R/2020/277	27 October 2020	11 December 2019 – 9 January 2020	An internal electrical contact in the engine control unit might not meet specification; the unit is replaced.
R/2021/202	21 July 2021	30 November 2016 – 28 February 2017	A bore in the steering-shaft universal joint might be outside specification; the shaft is checked and replaced if needed.
R/2023/062	13 March 2023	7 May 2015 – 4 April 2017	Diesel engine-control software did not meet local legal requirements; the software is updated.
R/2024/166	6 May 2024	2 July 2018 – 31 January 2024	The backup function in the electric-steering software might not meet specification, which could impair assistance; the steering software is updated.

MOT watch-points

What the 2024 DVSA figures say

First-time pass rate: 72.6% from 72,744 normal Class 4 and 7 Mercedes-Benz B-Class tests.
National comparison: 71.5% across the same 2024 dataset, so this model was 1.1 percentage points above the national first-time pass rate.
Typical tested mileage: median 64,423 miles; mean 68,227 miles.

Most common recorded failure reasons

DVSA failure reason	Tests	Share of this model's tests
Coil spring: fractured or broken	2,336	3.2%
Malfunction indicator lamp: inoperative or indicates a malfunction	1,728	2.4%
Linkage ball joint dust cover: ball joint dust cover no longer prevents the ingress of dirt	1,548	2.1%
Ball joint: ball joint excessively worn	1,540	2.1%
Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt	1,527	2.1%

One test can record more than one defect, so the shares must not be added together.

Common advisories to check before buying

Tread depth: worn close to legal limit/worn on edge — recorded on 16.4% of tests.
Tyres - condition: slightly damaged/cracking or perishing — recorded on 10.2% of tests.
Brake discs: worn, pitted or scored, but not seriously weakened — recorded on 8.3% of tests.

Method and limits: C4R calculated these figures from DVSA's anonymised 2024 MOT results. Pass rate is P / (P + F + PRS) for normal Class 4 and 7 tests. Results are de-duplicated by test, low-volume rows are suppressed, and DVSA model labels are standardised into a model family. These figures describe tested cars as a group; they do not predict the condition of one vehicle or prove that every trim and generation performs the same way.

DVSA anonymised MOT tests and results · Open Government Licence v3.0

Contains public sector information licensed under the Open Government Licence v3.0. Source: DVSA anonymised MOT tests and results, 2024.

The failure data makes springs, ball joints, driveshaft boots and warning lamps sensible inspection priorities, even where the test drive feels normal.

Buying one? Our checklist

Check the registration for outstanding recalls, especially R/2024/166 on W247 cars.
Diesel: inspect the service and usage history, then investigate any DPF or engine warning before buying.
W246: test stop/start after a proper drive and ask when the starter battery was last tested or replaced.
Automatic: test from cold, in slow traffic and in reverse; reject warning messages or pronounced judder pending diagnosis.
Drive over a rough road with the radio off, then inspect springs, ball joints, driveshaft boots and tyre wear.
Check both keys, the folding rear seats, tailgate, air conditioning and every fitted electrical option.
Read the online MOT history for recurring advisories rather than relying only on the latest pass.

Sources & further reading

Contains public sector information licensed under the Open Government Licence v3.0.

See Mercedes-Benz B-Class cars for sale on C4R