Mercedes-Benz B Class Common Problems and Solutions
Crunching Gears
Problem:
Your gears make a crunching or whining sound when you're driving. Sometimes, you get stuck in gear, and you may even jump out of gear occasionally.
Solution:
Your gearbox is faulty and will need to be completely replaced. You can easily buy a new gearbox from us, and it's a lot easier to remove and replace the existing one than you might think. This can be a very serious issue, and you will need to address it quickly. A faulty gearbox can easily lead to accidents when driving.
Difficulty level
Gearbox Transmission
Knocking from Front Suspension
Problem:
You can hear a knocking sound from the front of the car when driving.
Solution:
The anti-roll bar bushes in a Mercedes-Benz B-Class are very durable, but they don't have an infinite lifespan. If you can hear knocking from the front suspension, then you will need to find replacement anti-roll bar bushes on our list of parts and replace the worn ones.
Difficulty level
Anti Roll Bar Bush
Increased Fuel Use and Odour (All Diesel Models)
Problem:
You are using more fuel than you used to, and you can smell the fuel inside the car. You might also notice a 'huffing' sound from your engine.
Solution:
There is very likely going to be a problem with your injector seals. Check the O-ring that's fitted to the injector for any cracks. If you find any damage, you can buy a replacement O-ring on our site and install it easily. If there are no issues with the O-ring that you can see, then you may have a problem with the injector body. In that case, you will need to buy and install a new injector.
Difficulty level
Car Goes Into 'Limp-Home' Mode
Problem:
The engine will trip into limp-home mode.
Solution:
Your particulate filter is clogged. You will need to clean it out, and it's far cheaper to do this yourself. You can avoid this issue by going for regular motorway runs.
Difficulty level
Seat belt failure
Problem:
The seat belts on the B-Class are prone for wearing down early. The outside edges can fray or rip.
Solution:
Replacing the seat belts can be expensive. We can help you find a replacement seat belt at a very low price.
Difficulty level
Air conditioning whirring noise
Problem:
The air conditioning pulleys are known for failing. When you switch the air conditioning on full and hear a whirring noise coming from the engine, this is an indication that the pulleys are faulty.
Solution:
Replacing the air conditioning pulleys will sort the problem.
Difficulty level
Aircon Pulley
Injector seal failure
Problem:
The injectors seals can fail on the B-Class vehicles. When you turn on the engine and you can hear a sort of chaffing noise coming from the top of the engine and/or feel a vibration through the car, then the injector seal is the most likely cause.
Solution:
You will need to fit a replacement injector seal to rectify the situation.
Difficulty level
DPF warning light
Problem:
If the DPF (Diesel Particulate Filter) warning light has appeared on the dashboard, it means your DPF is clogged up. Vehicles fitted with a DPF are not really suitable for short journeys around town etc, as this does not allow the DPF to get hot enough to burn off the harmful particles.
Solution:
The first thing to try is taking the vehicle out onto an open road and driving at around 2500rpm in fourth gear for 5-10 miles to allow the DPF to get hot enough to burn off the particles that are causing the blockage. This should turn off the DPF warning light on the dashboard. If it does not, then it means that you have either a failed DPF sensor or you need to remove the DPF to clean it out manually. If you need to clean it out manually, the video below shows one way to do it:
Difficulty level
Uncomfortable Passenger Seat
Problem:
The front passenger seat is uncomfortable to sit on.
Solution:
This caused a recall on all Mercedes-Benz B-Class models built between 2015 and 2017 and is down to faulty specification used in the cushion. You will have to buy a replacement cushion from our pages and replace the existing one.
Difficulty level
Engine Control Unit Failure
Problem:
The ECU either stops working or cuts out intermittently.
Solution:
This is due to the incorrect electrical contacting that's inside the engine control unit. You will need to browse through our list of ECUs that will fit a Mercedes-Benz B-Class and replace the existing one.
Difficulty level
ECU Engine
