MERCEDES A Class (2005-) Fault Guide

Evolutions

Year Change or development
2005 Revised A Class introduced. Full specification and engine information is available in our figures and specs section.

Bodywork and External Checks

Area What to look for What it means What to do
Rust Inspect the bodywork for signs of rust and corrosion. Pay particular attention to the areas around the wheel arches, the lower edge of the boot and the door seals at the lower edges of the doors. If you find areas of rust these will need to be treated as soon as possible to stop the rust spreading. The rust needs to be cut away and the body work made good. A rule of thumb is that each spot of rust will cost £100 - £200 to fix. If you find this fault and the car is under warranty (3 years) then Mercedes Benz may fix the problem for free. Otherwise try to reduce the price of the car by £100.00 per rust spot found.
Wipers Test drive the car. Make sure the windscreen washers work both back and front. If the front washers are broken or not working very well then the car will need to have the washer jets and hoses replaced. If the rear washer is broken then the hose in the boot will need to be re-attached. If the front jets are broken then try to reduce the price of the vehicle by £120.00 per. If the real jet has failed then try to negotiate a price reduction of £60.00 off of the price of the car.
Rear Hatch Stand by the rear hatch and manually open and close the hatchback four or five times. Make sure the hatch opens cleanly each time and does not stay closed when the catch is pulled. If you find this fault then the boot lock will need to be replaced. If you find this fault then try to reduce the price of the car by £110.00.
Keys Make absolutely sure that the car has two keys. If the car lacks a second key then it will be very expensive to have another cut and programmed with the correct code to unlock the doors. If the car lacks a second key then try to negotiate a price reduction of £350.00 off of the price of the car.

Engine Checks

Area What to look for What it means What to do
Servicing Check the service history to see if the car is due an additional service. In the A-Class the brake fluid service and the air and fuel filter service are not part of the standard servicing. People often sell cars when these services are due. The brake service is due every 2 years and costs £80.00. The air and fuel filters are due every 4 years and cost £50.00. If you find an additional service is due then try to reduce the price of that vehicle by that amount.
DPF Check the service history and see if the car is fitted with a DPF (Diesel Particulate Filter) – this was a factory option and not all cars have it. Check the DPF (Diesel Particulate Filter) warning light on the dash comes on with the ignition and goes off after a few seconds. Check that the engine management warning light is not on at the same time as the DPF warning light. The DPF is there to remove harmful particulates from the exhaust when the car is running. Diesels with DPF are not really suited to small runs and town driving/school runs in particular as the filter does not get hot enough to burn the particulates off and it gets clogged up. Running the car at 2500 rpm for 5/10 miles in 4th gear should allow the DPF to get hot enough to burn off the particulates clogged up inside. If doing this does not cause the DPF warning light to go out then the DPF will need to be manually cleaned out by a main dealer. If either the DPF warning light or engine management warning light stay on (or the car goes into Limp Home mode) then have car inspected by a qualified mechanic. Otherwise, negotiate a discount of £180.00 and have the DPF manually cleaned out by a main dealer.
Diesel engines Test drive the car. Start the car and, ideally with the engine cold, listen for a train like ‘chuffing’ from the top of the engine and a similar vibration through the car. Check for the smell of diesel in the cabin. These faults may indicate failure of the injector seals in the engine. If you find this fault and the car is under warranty (3 years) then Mercedes Benz may fix the problem for free. Otherwise try to reduce the price of the car by £480.00.

Interior Checks

Area What to look for What it means What to do
Air conditioning Turn on the engine and put the air conditioning on full via the controls on the centre console. Listen carefully for a loud whirring noise coming from the engine. This can mean a fault with the air conditioning pulleys which are driven by the engine and power the air conditioning. If you find this fault and the car is under warranty (3 years) then Mercedes Benz may fix the problem for free. Otherwise try to reduce the price of the car by £200.00.
Locks Use the electronic key fob to unlock the doors. Stand next to the front passenger door as you do this and listen out for the door rapidly locking and unlocking itself. Repeat his process several times, on all four doors, and check for the same fault each time. If you find this fault then the locking mechanism on the affected door will have to be replaced. If you find this fault and the car is under warranty (3 years) then Mercedes Benz may fix the problem for free. Otherwise try to reduce the price of the car by £500.00.
Clutch As you let the clutch out, notice where the vehicle first starts to move. This point on the clutch's travel is the bite point. If this point is high (near the end of the pedal's travel) the clutch will fail soon. When this vehicle's clutch is nearing the end of its life, the most common symptom is a high bite point. The clutch is expensive to replace on the A-Class because the engine has to come out to get at the clutch. If you find this fault try to negotiate a discount of £1000.00 off of the price of the car.
Air conditioning Check to see if the air-conditioning is working properly. Sit in the driver’s seat and turn on the air-con via the button on the centre console. The red light should go out. If it stays on then the air-con will need a re-gas. The air-con will need to be re-gassed to make it function properly. If you find the air-con needs a re-gas then try to reduce the price of the car by £110.00.
CVT Automatics Test drive the car. Check the functioning of the CVT automatic gearbox. Make sure the box does not judder as the car goes in and out of drive. Also listen out for a whining, chainsaw like noise from the gearbox when the car is moving. Either of these problems could be caused by failure of the CVT box. This will need to be replaced which entails removing the engine. If you find this fault and the car is under warranty (3 years) then Mercedes Benz may fix the problem for free. Otherwise try to reduce the price of the car by £3000.00. If you suspect a fault with the CVT box then it is advised to have the car inspected by a professional mechanic.
Manual gearbox Test drive the car. Make sure that first gear and reverse can be selected easily with no stiffness from the box as these gears are selected. If it is difficult to engage first gear and reverse then it may be because the lay shaft to be lubricated. This is very expensive as the engine and gearbox need to be removed. If you find this fault and the car is under warranty (3 years) then Mercedes Benz may fix the problem for free. Otherwise try to reduce the price of the car by £1900.00. If you suspect a fault with the gearbox then it is advised to have the car inspected by a professional mechanic.

Wheels, Brakes and Suspension Checks

Area What to look for What it means What to do
Tyres Inspect the outside edges of the front tyres. The legal limit for tread depth is 1.6mm above the base of the groove across 75% of the tyre. Check for signs of uneven wear. If you find uneven wear on the front tyres then those both tyres will need to be replaced and the tracking re-set. If you find that tyres will need to be replaced then budget £60.00 for each tyre. Also try to negotiate a further £90.00 to have the tracking done.
Suspension Test drive the car. Listen for a knocking from the front suspension as the car passes over bumps. If you hear this knocking, it is likely to be caused by wear to the anti-roll bar bushes. If you find his fault then try to negotiate a reduction of £300.00 off of the price of the car.
Brakes Look through the middle of the wheels to the brake discs. They should have uniform wear all the way round. They should not be pitted. If the brakes are cold, feel the disc through a gap in the wheel. It should not be pitted or scored, nor should it have a large lip on the edge of the disc (a large lip is a few millimetres). The disc should be evenly worn across the face of the disc. If you find either of these problems then the brake discs (and pads) will need replacing. If you find this fault then try to negotiate a discount of £260.00 per affected axle.

Recalls

Date Model Recall
19 Dec 2005 A Class It has been identified that during the manufacturing process a notch may have been formed on the wiper arm, which in extreme cases can cause the arm to fracture.
14 Oct 2008 A Class Seat belt locking pawls may break in the event of an accident which in the most unfavourable circumstances may lead to the seat belt buckle detaching.
10 Nov 2008 A Class built: 01/01/2004 - 08/10/2008. Possibility of transfer of incorrect control unit software which could affect engine shut off control in an emergency situation or the on board diagnosis system or tank/speedometer signal
30 Sep 2010 A Class It is possible on some fuel tanks that the vent pipe is not to specification. This can lead to a small leak into the charcoal canister and if not rectified, can, over a period of time, result in a fuel leak.

Recommended Garages

Name Phone Address Website
MOT ANGEL (Nationwide) 0800 131 0030 3 The Minster, Portman Road, Reading, RG30 1EA. http://www.motangel.co.uk