EXPERT IN AUTO PARTS
19 March 2025 Table of content
The 7G-Tronic transmission in the Mercedes B-Class is prone to shifting irregularities, especially in the 2008-2012 model years. Typical symptoms are jerky gear changes, extended shift times or the transition to emergency running. The causes are often worn multi-plate clutches, defective solenoid valves or outdated control unit software.
A systematic check is crucial for the service life of the transmission. The complex Mercedes B-Class automatic transmissions require an oil change with specific MB 236.15 oil every 60,000-80,000 km. Diagnostically, the adaptation values and fault memory should be read out first. In the event of mechanical defects, experts recommend replacing the clutch packs or a general overhaul of the transmission, whereby the costs depend heavily on the type of damage.
In models with 1.6L and 1.8L petrol engines, excessive timing chain stretching often occurs after 80,000 km. Critical signs are rattling caused by the starting phase, misfiring or a sudden drop in oil pressure. The elongation tolerance must not exceed 3 mm per 100 chain links - a value that must be checked using special measuring tools.
Professional maintenance is essential for the reliability of the drivetrain. The susceptible Mercedes B-Class timing chains from the 2007-2011 model years require a visual inspection of the tensioner rails and chain tensioners every 60,000 km. In the event of complaints, the complete Mercedes B-Class timing chain kit (chain, guide rails, tensioner) should always be replaced to avoid consequential damage to the camshaft bearings.
Diesel versions from 2008 onwards in particular show starting problems after 120,000-150,000 km due to defective fuel feed pumps or faulty CAN bus communication. Voltage measurements at the pump and a check of relay R10 in the SAM control unit are diagnostically relevant.
BREMBO Brake disc
295x28mm, 5, perforated/vented
Article number: 09.B436.51
£ 36,12
Price per item
price incl. 20% VAT, excl. delivery costs
BOSCH Sensor, exhaust pressure
Article number: 0 281 006 278
£ 22,26
price incl. 20% VAT, excl. delivery costs
-28%
Article number: V20-4300
compared to
RRP
£ 148,14
£ 106,03
price incl. 20% VAT, excl. delivery costs
BOSCH Water Pump, parking heater
12V, without holder
Article number: 0 392 023 004
£ 45,28
price incl. 20% VAT, excl. delivery costs
-14%
Article number: MN7501-10
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compared to
RRP
£ 32,53
£ 27,93
£ 2,79 for 1 litre
price incl. 20% VAT, excl. delivery costs
A professional inspection can prevent expensive towing costs. The electronics-intensive Mercedes B-Class engine management systems require immediate diagnosis at the first sign of trouble. As a preventive measure, we recommend replacing the high-pressure pump every 200,000 km and using diesel additives to improve the lubricating properties.
Electrical failures of the Mercedes B-Class tailgate locking system particularly affect the W246 models. Corroded contacts in the actuator or defects in the control lever in the cockpit are usually responsible. A temporary workaround is manual opening via the emergency release cable behind the rear seat backrest.
Regular maintenance prevents malfunctions. The sensitive Mercedes B-Class locking systems require the contacts to be cleaned with contact spray every 30,000 km. In the event of permanent defects, the entire actuator must be replaced, whereby a software adjustment via XENTRY is necessary in order to teach the component correctly.
The Mercedes B-Class has an advanced infotainment system, but it can sometimes have errors such as frozen screens or unresponsive touch controls. These problems can often be fixed by software updates, but persistent problems may require hardware repair or replacement of the system. Regular maintenance of the car electronics and, if necessary, replacement of defective components can help to ensure the reliability of the system.
A systematic check is essential to detect these problems at an early stage. The Mercedes B-Class infotainment systems require regular software updates and, if necessary, the replacement of defective components to ensure optimum function. Professional maintenance can help to identify and rectify such problems before they lead to major damage.
Article number: P 50 094
£ 21,85
price incl. 20% VAT, excl. delivery costs
-11%
Article number: MN7715-10
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compared to
RRP
£ 41,34
£ 36,70
£ 3,67 for 1 litre
price incl. 20% VAT, excl. delivery costs
-26%
Article number: MN7511-4
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compared to
RRP
£ 19,34
£ 14,19
£ 3,55 for 1 litre
price incl. 20% VAT, excl. delivery costs
Article number: 04947
£ 2,33
Price per item
price incl. 20% VAT, excl. delivery costs
-43%
FANFARO Transmission fluid
75W-80, Full Synthetic Oil, Capacity: 1l
Article number: FF8710-1
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compared to
RRP
£ 11,22
£ 6,29
£ 6,29 for 1 litre
price incl. 20% VAT, excl. delivery costs
Based on owner testimonials, the following weak points can occur:
| Strengths | Weak points |
|---|---|
| Spacious interior | Susceptible timing chains |
| Good crash safety | Electronic faults |
| Economical diesel variants | Complex transmission electronics |
| High-quality workmanship | Susceptibility to corrosion in brakes |
| Innovative infotainment | Expensive spare car parts costs |
| Good suspension comfort | Frequent AdBlue system problems |
| Long service life for gasoline engines | Sensitive filling station sensors |
The Mercedes B-Class impresses with its practicality and comfort, but requires intensive maintenance at higher mileages. Critical assemblies such as the timing chain and automatic transmission should be checked regularly from 80,000 km. However, with preventive measures and professional maintenance, many of the typical weak points can be effectively avoided, which significantly increases overall reliability.
BOSCH Oil filter
M 20 x 1,5, Spin-on Filter
Valvoline Engine oil
5W-30, 4l
MANNOL Engine oil
5W-30, 5l
FEBI BILSTEIN Antifreeze
G11, blue, 5l, Concentrate
LIQUI MOLY Engine oil
5W-30, 5l, Synthetic Oil
ATE Handbrake shoes
with accessories
OPEL GM Engine oil
5W-30, 1l, Synthetic Oil
MOBIL Engine oil
5W-40, 5l
BOSCH Parking sensor
Ultrasonic Sensor
VALEO Wiper blade
650 mm, Flat wiper blade, Hook fixing, Top Lock, Pin Fixing