BMW N20 Problems to Expect – Reliability Report

Hey guys and welcome back to the SimpleCarGuy channel. So, you are looking at a BMW with the N20 engine and want to know how reliable it is? Well, you found the right video as today we will be talking about the common issues, best and worst years to buy, what to do if you already have this engine in your car and my experience after 2 years with this car.


We’ll start with a little background and history as I think it’s important to understand before we talk about the common issues and problems. I swear this will only take a minute! The BMW N20 engine was designed to replace the N52 and N53 6 cylinder naturally aspirated engines that were among the most reliable engines produced by BMW and used in most ‘common’ BMWs. Even though the N20 engine is a 4 cylinder, it produced similar power figures and powered equivalent models. Of course, this means the engine has been turbocharged, direct injected and used other top of the line technology for 2011 to achieve this performance.

There were a few different version of the BMW N20 engine manufactured from 2011 to 2017 and used in many different vehicles. Europe and other countries have the optional lower power 180hp version in their 320i, 420i, 520i and other ‘something’20 cars, but in North America we only had the 240hp version and that’s the version I will concentrate on in this video since the biggest difference is actually tunning and support components and not the engine itself. So, it mostly applies to both. North America got this engine in the Z4 (point to it), X1, X3 and X4 SUVs, 3, 4 and 5 series and even in the sDrive40e X5 where it was mated to the hybrid electrical motor. So, clearly it was used across most of the BMW range. [Show which cars it was in on the screen like I had the list in the emergency kit video]

Common Issues:

Alright, so what are the common issues then? The worst common issue on the BMW N20 engine has to be the timing chain issues that have been discussed at length. To summarize, BMW has used brittle plastics for the timing chain guides which break or crack after a certain period of time causing the timing chain to get loose and eventually skip timing, eventually destroying the engine. Hopefully it never gets that far and you notice the chain rattle way before that and get the chain replaced. In some cases, the chain tensioner is the culprit behind the loose chain and since it’s very easy to change, it can be a good first step before taking the engine apart.

The second big issue on the N20 engine is the rod bearing failure. This one is even more serious, but luckily not as common as the chain guide issue. If you start hearing a slapping type noise like this, you might be looking for a new engine. While the rod bearings are not impossible to replace, unfortunately, the crankshaft gets damaged in the process as well and to fix the journals on the crankshaft, the entire engine has to be taken apart. If there is any hint of rod bearings going bad on your engine, it’s time to replace those NOW.

With the scary items out of the way, let’s talk about some of the common issues that you can probably DIY or get done without spending a fortune. Just like with the N52 and N53 engines, the valve cover is plastic and has a tendency to crack and/or leak oil. This wouldn’t be a huge problem, but it usually leaks all over the exhaust and O2 sensors, which can be damaged in the process… not to mention the smell of burning oil.

Similarly, the oil filter gasket issue has been carried over from the older engines and can leak. Luckily this one is very easy and inexpensive to replace, but if it’s not replaced, it will leak all over the serpentine belt which can cause some serious engine damage.

We are getting closer to the end of the list, but there are a few more items to mention. As we know this is a turbocharged engine and as such it has a wastegate. Unfortunately, the design of it allows the wastegate flapper to get loose overtime and start making a noise. This wastegate rattle isn’t a huge problem at first as it just makes an annoying noise, especially when you start the car, but the looser it gets the more of an issue it can be as it won’t hold boost and degrade performance of the engine.

This engine is also direct injected as mentioned earlier and produces low emissions, which is great but it also means that carbon build up isn’t uncommon. The injectors themselves are also pretty high tech and can fail causing drive train malfunction messages and stuttering of the engine while driving. Check out this video on how to replace the injectors on this engine in the top right corner or the description.

The last item I want to talk about on the N20 engine is the high-pressure fuel pump. These were a huge problem on the N54 engines, but luckily not as huge of a problem here. They still do fail on these engines but at least they are not as expensive and can easily be replaced in half an hour. I’ve done it on this engine and here is how.

As these engines are becoming older and older, it’s also a good idea to check the coolant hoses for cracks, make sure the chargepipe is not cracked and inspect the vacuum lines for any leaks. The most expensive part of fixing BMWs is the labor, so maybe it’s good to tackle some of the easier projects yourself and learn more about your car in the process.

Best and Worst Years:

So, what issues got fixed over the years and what are the best years to buy then? [put this on the screen] In most cases, that doesn’t really matter, but with this engine there is a big difference. The only N20 engines I would recommend would be the ones build in 2015 and later as they have fixed most of the issues discussed here on those models. They improved the timing chain guides, changed the injectors to EU6 from EU5 and improved the overall reliability. If you are considering a BMW with the N20 engine between 2011 and 2014, I would make sure that all of the issues we discussed have been taken care and the maintenance has been on time, but especially the timing chain replacement.


What can you do?

Now, it may sound bad on the surface and I’ll admit it’s not the best engine in the world, but these engines are in thousands of vehicles and a lot of them have no issues at all or the issues have already been fixed. So, as with most BMWs, if you take care of them properly and do some extra maintenance they will last much longer. A few examples of that would be to check your oil every other fill up and change your oil every 5k miles and not every 10k miles as recommended by BMW. This will help with preventing rod bearing failure. Also, check for oil leaks and take care of those fast before they cause more damage and a lot more expensive repairs in the future. Lastly, if the timing chain has not been replaced on your early N20 engine, get it done before it’s too late!

Personal Experience:

As for my personal experience, I bought this BMW Z4 with a bad engine, but looking at its history, it was maintained by the dealer as per the book. You can follow my early videos on this car where I go through the process of replacing the timing chain, HPFP, injectors, fixing the wastegate rattle and eventually tearing apart the broken engine to reveal the damage done by a spun rod bearing. However, ever since I installed a 2015 engine in this car, it has been running like a dream for the last 2 years.


All in all, this is not a bad engine, especially after the improvements done for 2015 and newer models and the other issues are only becoming common on engines with very high mileage. A lot of it also has to do with how the engine was taken care, driven and of course some luck on how it was built that day at the factory. With any luck, a well taken care of BMW N20 engine should be reliable and also inexpensive to maintain while providing a smooth, enjoyable and sporty drive. Stay tuned for the reliability video on the N55 and N63 engines in the near future, thank you so much for watching and I’ll see you in the next one!