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BMW Common Faults

Check engine light on? Engine running rough?  Here you will find some answers to the most frequently diagnosed BMW problems brought into TWG.  We do not recommend you assume that the answer here directly relates to your car.  Accurate diagnosis of a problem typically saves you money.  And, you should know that often third parties will misdiagnose a car for what appears to be similar problems or related diagnostic codes. Also ever heard the saying “a little knowledge is dangerous” its true! to much Googling can cost you extra money if you assume your problems are related. Here are some common issues we have experienced at TWG Sport.

Steering Wheel Vibrates Under Braking

This is very common on the 3 series. Initially, under light braking, the steering wheel will shake. As this problem gets worse the steering wheel will shake more and eventually the actual road wheel will visibly move back and forth under braking. Left alone this problem can cause significant damage. If you catch it at the earlier stage, usually replacing the control arm pea bush will resolve the problem. However, left for a longer period, the vibrating can cause ball joint failure on the front end of the control arms and brake disc warping.

​Check Engine Light – Runs Rough

There are many reasons why a check engine light and rough running could occur. Different models have different common issues. Usually the rough running is a sign of misfires – this is often caused for example, on the V8 engines by a failure of the ignition coils or a collapsing vacumn hose. On the 6 cylinder engines, rough running when the engine is cold can often be caused by a failure in the PCV valve system. This is extremely common in cold weather states and was originally subject to a recall. If left unchecked, the valve can actually pull oil from the sump into the combustion chambers and as in one case we saw, actually oil lock the engine.

​BMW Timing Chain

The N47 and others fitted with single row chains are prone to excessive timing chain wear and premature failure. Rattling noise from the rear of the engine is indicative of the condition. Timing chain failure may call for engine rebuild.  The issue applies to all applications and power variants of the engine produced from 01.03.2007 to 01.03.2011. The most seriously affected units which require the most extensive repairs were produced from 01.03.2007 to 01.03.2011.

Any rattles turn of the engine and recover to TWG we have seen many of these engine’s survive just with a replacement chain kit price about £1500 not 4k to 5k! what other garages may charge.

BMW Swirl Flaps

The BMW inlet manifolds on certain diesel models have swirl flaps which are designed to create a swirl of air to improve exhaust emissions and fuel consumption. The flap is closed by an actuator during light load, idling and fully open during engine load to maximise air intake and increase engine output.

The common problem with swirl flaps is when they fail, the rivets/screws can get swallowed into the engine causing damage to pistons, valves, cylinder heads and damage to the turbo.

BMW swirl flap failure can result in a complete engine replacement costing thousands.

Blower Motor Will Not Run

This is very common on the older 3 series and 5 series vehicles. The HVAC blower either does not run or runs at 1 speed. The common cause of this is the blower motor resistor often called the hedgehog due to its look which controls the speed at which the blower operates, easy to replace.

BMW Blocked DPF


The electronic indicator lights, the vehicle has no more power and extremely high fuel consumption? The diesel particulate filter has only a limited capacity to store particulates. From a certain amount of soot, the soot particles must be burned in a regeneration process to CO2 and ashes. Different reasons can mean the regeneration process does not start and in consequence the DPF gets clogged with soot particles.

Possible causes:

  • Defective or not fully functioning injectors
  • Sooty or coked EGR valve
  • Different qualities of fuel or Bio fuels
  • Short distance driving profile


Particulate filters can be cleaned in an installed condition, rapidly, simply and significantly more economically than replacing them.

  • Used when regeneration is no longer possible
  • Cleaning to almost new condition possible
  • No expensive new installation
  • Cleaning without disassembly of the particulate filter
  • Non-flammable
  • Neutral ash and metal-free formulation
  • Evaporates completely

Compatible with other materials

An overloaded DPF: That is expensive.

For replacement of the part customers have to pay a lot of money. For a new diesel particulate filter between £600 and £4000 would be charged. In addition a prolonged stay in the workshop and a rental car has to be organised. TWG Solution: Cleaning instead of replacement.