This blog is dedicated to BMW petrol engines, so let’s talk about petrol engines.


Quite often I happen to hear – from BMW users, internet forums, even BMW service centers – the N series of BMW engines is a fail. They are not long lasting anymore, they encounter never-ending problems. Quite often such problems can not be solved.


I say – BMW manufactures excellent petrol engines.


Yes, you can oppose – these N series engines are complicated, have many different and complicated systems, so “everything is bad”. No, actually the problem is not with the engines – the problem is will underqualified repair staff! Yes, we can blame BMW AG regarding fact, that the information regarding structure and maintenance is insufficient, and that is true.


There are people, who claim, that BMW has reached “almost nothing” in the progress of engines during several decades. I will mention just one example from my experience.

20 years ago I had BMW E32. A great car for longer drives – wide, stable, with the smooth run. But its M30B35 series 3.4-liter engine had around 200 hp and was very irresponsible. Fuel consumption: at least 10 liters/100 km, driving with cruise control around 90 .. 100 km/h. N53B30O0 series engine with 3.0 liters displacement has close to 300 hp; almost full torque available in a range from 1300 to 6500 RPM, the engine is very responsible, with momentous reaction. Fuel consumption? Half of the M30 engine’s consumption! And the power (around 100 hp from 1 liter), which is available for most powerful versions of N52 and N53 series engines – in the past, it was available only for S series engines!


You will oppose – it’s not so bad with the maintenance of the modern engines! Below I will gather my own experience and also the experience of other BMW users.


Let’s start with a very simple task – maintenance. Oil change.

For example, a typical situation for an N53 series engine – when adding the oil, it leaks along the filling cork to the shaft of the spark plug of cylinder No.3. During the time, the dirt, gotten into the shaft, and oil create current leakage, and misfiring problems of cylinder No.3 can begin. It’s a common problem. But when I talked (and also showed it) about this issue with specialists in specialized BMW service center, they replied shortly – it’s not possible!


The second part of the maintenance – replacement of spark plugs. I called a local BMW AG dealer in the region. It’s service center manager to my question “When the spark plugs for N52/N53 series engines have to be replaced?” answered – never! When I asked once again, how is that possible, he clarified “when the strong shivering starts… But there are no exact intervals.”

I will clarify: for N43/N53 series engines, the spark plugs have to be replaced after each 20 .. 30 k km (they are wearing out much more quickly as in “old” engines because these modern engines use multi-ignition. If the shivering has already started – after replacing the spark plugs, the engine has to be re-adapted.

I witnessed the situation when in the BMW dealer center the owner of a car with the N53 series engine was asked – “would you like to have spark plugs with iridium or platinum electrodes”? I just have to remind you, that the spark plugs for N43/N53 series engines are produced by only one manufacturer, and there is only one model of them!

For new engines the replacement of spark plugs has to be done very carefully – the situation, when the oil gets on the spark plug and ignition coil, is not acceptable. When I pointed this out in the local specialized BMW service (when noticed, that all instruments are oily, and also the hands of the person, who performs the operation, were oily), the maintenance specialist argued, that I ask for something impossible, they don’t work like that. And added, that such him he hears for the first time.

Unfortunately not INPA, not ISTA D don’t display problems of the ignition system (misfire counters). Accordingly – if the uneven performance of the engine continues, “specialists” usually replace all ignition coils. Correct solution – use an ELM327 adapter and detect the damaged ignition coil.

And finishing the part regarding maintenance – the nightmare of N series engines: oil exchange after the interval, scheduled by the manufacturer (around 25’000 km). If you replace the oil after each 10 .. 15 k km, you can drive around 300 .. 400 k km or even more without serious repairs!


Mechanical hub, which, in my opinion, applies to check out of the engine, when performing its maintenance: CCVV. The rubber membrane of the valve has a limited lifespan, if it’s damaged – increased oil consumption, shivering of the engine in idle are guaranteed. Unfortunately, usually, none of “specialists” in the service center knows, how to check the CCVV. The wear of the engine is mentioned as the cause for increased oil consumption (so the myths regarding the short lifespan of N series engines are born), but for the shivering, the (non-existing) defects of injectors are blamed. The damage of CCVV causes the error messages regarding fuel mixture, signals of Lambda probes. When the mentioned Lambda probes are spotted in the description of the error message, they, of course, are replaced. When it doesn’t solve the problem, the “specialist” claims, that the problem is unsolvable.


The typical hub of N series engines (except N43/N53) – Valvetronic. In my experience, unfortunately, I never met any specialist in the service center, which would understand, how this hub functions, and how it’s performance can be affected by each component. Typical reply – in case of uneven performance of the engine “I replace everything, then usually it calms down”. Typically such repair includes camshafts and eccentric shaft, intermediate levers, replacement of other Valvetronic components; HVA; spark plugs, ignition coils. Of course, “replacing everything”, the situation may improve. True though, as almost none of them has heard about the procedure of re-adapting the engine (what is it and why it’s necessary), the shivering of the engine very often continues. But, as the repair specialist “vulgaris” don’t know, how to use Rough run menu, don’t know the basic performance principles of MSV/MSD management units, to customer claims, that the engine doesn’t perform perfectly, he just claims, that so these engines work. Did everything, what could be possible!


Only in separate cases even the specialist of specialized BMW service centers understand, how do VANOS works and which components have to be replaced in case of exact problems. Not taking into account, that these hubs are used for already more than 20 years, and there are many descriptions of how they work. A good thing, that both VANOS (if also the camshaft of the exhaust is equipped with this hub) have equal sensors and valves – these parts can be changed by places, trying to find the damaged one – it’s a typical method when there is no knowledge. Of course, the owner of the car will pay for time, used for this “diagnostics”.


The situation with fuel systems of newest engines (N43/53/54/55) is even more pitiful. The error message regarding HPFP? It has to be replaced! In my experience I have diagnosed only one faulty HPFP for an N43 engine – it’s one case of several thousand. More exactly -the valve of the HPFP of the current faulty N43 engine was stuck (unfortunately, the HPFP valve of N43 series engines is integrated into the pump, it can not be disassembled or repaired). What is a typical error message regarding HPFP? Usually – regarding a decreased pressure at the moment of the engine start. The cause of this problem – typically: leaking injector or (rarely) – non-airtight HPFP valve. Accordingly, at least 90% HPFP is replaced without a reason! A good thing, if it happens during warranty time.

One, also quite common, situation – HPFP is replaced, even if the error message is recorded regarding LPFP. Or – the error message regarding HPFP is recorded in obstacles when it receives decreased fuel pressure (obviously, the problem is with a low-pressure pump, which is located in the fuel tank)!


Many service “specialists”, when as if replacing the fuel filter, actually replace the charcoal filter, which is designed to recover the fuel vapor from the fuel tank. Quite a common situation even in dealer centers.


The situation with injectors is quite tragic. Unfortunately, ISTA D, which is available for a dealer, don’t give practically any information regarding adaptations of the injectors. INPA is not allowed in the dealer centers, but also a “simple” INPA installation includes MSD80 loader 1.001, which’s functionality is very limited. Loader 2.023 is very rare, but only it gives required information regarding tests of injectors. If data of injectors cannot be seen, a typical practice in dealer centers or in specialized service centers – if there are suspicions regarding problems of injectors (or any particular injector), all of them have to be replaced. And very rarely any of the specialists are able to encode (correctly) the injectors. Almost none – how to re-adapt the engine. As a result, at least in half on cases – no positive changes! Only unjustified expenses of several thousands of EUR.


The situation with specific problems (NOx system) – hopeless. Even in specialized centers are not able to recognize the problems of NOx catalytic converter and NOx sensor, don’t know, how to perform the desulphation of the NOx catalytic converter. For example, in the case of the error message 30E9 (damage of the NOx catalytic converter) they suggest replacing the NOx sensor etc.


This list of fails could be continued endlessly…


At the end – let’s come “back to the earth” from complicated cases. When my car, equipped with an N series engine, needed the replacement of the sensor of the crankshaft, I called the local BMW AG dealer. Sales “manager” asked – which one of two sensors has the problem? I opposed – “you mean camshafts, right?” No, he insisted, that he’s talking exactly about crankshaft! It has two sensors!

I didn’t succeed to convince the “manager”, that the crankshaft has only one sensor, but both camshaft sensors are identical, and it makes no sense to exactly point out, which one of them is faulty.

When I asked the director of the local BMW dealer service center – how do you improve your qualifications? Do you have after-sales training materials of N series engines? No, they don’t, because they haven’t inquired for them. No, they are not planning to inquire. Do they have any seminary? No, not in this region, and they are not also planned. No, they don’t have any considerable experience in repair of N series engines, but they think, they can handle it. I don’t think, this situation is unique… Unfortunately.


Examples, mentioned before, are only a small part of “fails”, which happens to several hundreds of repair “specialist” every day. Of course, the owners of the vehicles are those, who pay for them. But as a result of such fails due to lack of knowledge, the myths of capricious BMW engines, they short lifespan, and unsolvable problems are born.