BMW Petrol N43 Engine failures – How To Prevent

BMW Petrol Engine N43 Failures

Recently we have started to see engine problems / engine failures with BMW petrol engines – engine code N43. Failure can happen without prior warning and cause the engine to seize up, many repairs for this can run into the thousands with replacement engines needed.

What is causing the failures?

This is not down to a design problem, or a mechanical problem with the engine as such but more down to “long-life” servicing which can lead to oil changes occurring every 20,000 miles.
Combine this type of servicing with cars which have missed a service, gone overdue on a service, or even gone to a non-specialist garage where an incorrect oil grade is used during the service, and the result can be catastrophic.

The problem is the engine oil. Engine oil is not only designed to lubricate moving parts it is also used to control temperatures inside the engine, for example by cooling pistons, but also to absorb carbon. Carbon is by-product of combustion and occurs both in petrol and diesel engines.

As soon as you put new oil into an engine it is absorbing carbon from the moment you start the engine, when the oil is new this is not a problem the carbon is absorbed effectively and the car operates as normal. When the engine oil is “used” and has maybe done 10,000 miles + it becomes less effective, when the oil has done 15,000 + miles the oil can no longer absorb the carbon as it should and it starts to solidify or “sludge up” / “coke up” .This sludge then sticks to important engine components and can begin to block oil galleries and oil pumps.

Once oil pumps, and galleries begin to block up, key components begin to get starved of oil, this can quickely lead to permanent damage and failure, often resulting in expensive repairs.

Which engines are affected?

Primarily we are seeing engine failures on BMW petrol models with the engine code N43, this engine came out during 2007. The engine is fitted to 1 series and 3 series models ( from 116i – 320i ) .

However we have also experienced problems relating to oil quality with the previous petrol engine models from 2002-2007, again fitted to BMW 1 and 3 series models.
These engines carry the codes, N42,N45,N46.

Although we have not have engine seizures with these models we have experienced problems with the Variable camshaft timing ( know as VANOS ) Variable Valve Lift ( Valvetronic ) and the timing chains – all of which can be attributed to poor oil quality or coking up ( Where the oil has begun to turn to sludge )

How Can We Prevent These Problems?

Very simply by introducing an interim Oil and Filter change, around 8-10k miles or annually – maybe at the same time as the MOT for example.

Replacing the engine oil and filter ensures consistent engine oil quality which will protect the engine from any sludge build up, thus avoiding future expensive repairs

We at BM Automotive Solutions can carry out an Oil and Filter change using a Genuine BMW Oil Filter, and Castrol Edge 5w-30 Engine oil for as little as £99 including VAT

This Would Also include a Forte Engine Flush as standard – This will be run through the engine with the old oil and clean the engine from the inside out, removing any sludge and build up of carbon.

For Maximum protection we recommend adding the “3 can” BG treatment, this would also include an engine flush but also an Oil conditioner additive to add extra protection to the engine between servicing and also a Fuel treatment to clean and restore efficiency to the fuel injectors. An interim Oil and filter change with the BG “3 can” treatment is £145 including VAT

More information on the BG treatments can be found both here on BG Products informaton



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