Common BMW N20 Engine Problems (18i, 20i, 25i, 28i)

Are you interested in learning about the BMW N20 engine problems? Well, if that is the case, you’re in the right place!

In this article, we are going to learn everything when it comes to this engine, starting with the specs, common problems, as well as the applications of this engine. Finally, we will answer some frequently asked questions.

So, if you want to learn more about this engine, buckle up because it will be a long ride!

Basic BMW N20 Engine Specs

Like many automakers, BMW came to the conclusion that they should focus more on turbocharged applications starting in the late 2000s when strict environmental policies forced car makes to start “downsizing”. And since then we’ve seen the application of many turbocharged BMW engines, like the N20 for example.

The N20 was an inline-4 engine designed to replace the N53. So, what BMW wanted was to produce the same amount of power as with the N53 and improve the efficiency by adding a turbocharger to a smaller displacement engine.

And the N20 did that really well. There were two main configurations of this engine that we are going to cover next.

• N20B16 5 Series

This is a 1.6L inline-4 engine that has a redline of 7,000 rpm. The engine is rated at 168hp @ 5,000 rpm, while the torque is rated at 250N-m (184lb-ft) @ 4,700 rpm.

• N20B20 2 Series, 3 Series, 4 Series, 5 Series, X1, X2, X3, X4, X5, Z4 & Briliance Huansong 7 MPV

This is a 2.0L inline-4 engine that has a redline of 7,000 rpm. This engine comes in four different configurations. The least powerful version is rated at 154hp @ 5,000 rpm and 240 N-m (177lb-ft) of torque @ 4,500 rpm. While the most powerful version is rated at 241hp @ 5,000 rpm and 350N-m (258lb-ft) of torque @ 4,800 rpm.

Common BMW N20 Engine Problems

Now that we have familiarized ourselves with the N20 engine, let’s cover the all the BMW N20 engine problems.

Common BMW N20 Engine problems include:

• Timing Chain Failure
• Ignition Coil & Spark Plug Failure
• Excessive Carbon Buildup On Intake Valves
• Rod Bearing Failure
• VANOS Actuator Failure
• Wastegate Rattle
• High-Pressure Fuel Pump Failure
• Valve Cover & Oil Filter Housing Gasket Leak
• MAF Sensor Problems
• Water Pump Failure
• Charge Pipe Failure

Now that we briefly covered the problems, we can now move on and discuss them more thoroughly and try to understand how and why these problems happen.

Timing Chain Failure

The first issue that we want to cover and probably the most serious problem with the N20 engine is the notorious timing chain failure. This is a very common problem on this engine that happens quite often. So, it is really important to catch the problem on time before it gets too late.

What happens is that the timing chain often stretches and when there is too much stress the hydraulic tensioner can no longer support the chain. It is stretched at its maximum.

In these situations, the chain jumps and valves and pistons collide with each other. In this case, engine carnage happens and the engine is destined for the scrapyard.

Sometimes, the tensioners can break as well. You just never know with these engines. You can learn more about the N20 timing chain failures in BMW’s official N20 timing chain recall document.

Problems With Ignition Coils & Spark Plugs

Ignition coils and spark plugs are other very common failure point on these engines. These coils can easily last for the lifetime of the engine or they can fail unexpectedly.

When the ignition coil fails, you will get a check engine light and a misfire code. Replacing this coil will hopefully sort out the problem.

Also, a lot of people are pushing the spark plugs up to 100,000 miles, which is not a good idea. The best would be to replace the spark plugs every 50,000 miles, to be on the safe side.

Carbon Buildup On Intake Valves

The next problem is carbon buildup on the intake valves. These are direct injection engines. And as you know, they tend to develop carbon on the intake ports.

When there is too much carbon, the valve will not seat well and you will start experiencing misfires on a daily basis. The solution is to walnut blast the ports in order to clean the carbon deposits.

Rod Bearing Failures

Rod bearing failures are also present on these engines. They do not happen often like on the S54, S65, and S85 engines. But the bearings on the N20 can also fail and cause rod knock.

When you have a rod knock, you will start hearing how the piston rods basically hit the crankshaft. There will be a tapping noise present in the car. This problem will also scrap your engine in most cases.

N20 VANOS Actuator Failures

VANOS actuator failures are also common on the N20. These actuators are basically electronic solenoids that activate the VANOS system which is the variable valve timing.

You have one actuator per camshaft, so on this engine, there are two of them. They can fail, and you will be greeted with the check engine light. Replacing them is the only way to solve the problem.

N20 Wastegate Rattle

As you probably know, this engine implements a turbocharger. So, with the turbocharger, you also need to have a wastegate. This component regulates the exhaust gas flow.

And sometimes this wastegate can start to rattle. And this rattling can be really annoying to deal with. This is a common problem on many BMW turbocharger engines.

High-Pressure Fuel Pump Failure

This engine also has a high-pressure fuel pump since it is a direct injection engine. This HPFP unit can fail and cause problems.

If it fails completely your car will not be able to start and the only way to sort out this problem would be to replace the unit.

Valve Cover Gasket Oil Leaks & Oil Filter Housing Gasket Leaks

Oil leaks are another characteristic of this engine. The valve cover can crack or can leak from the gaskets. It is the same case with the oil filter housing.

The oil filter housing is made from cheap plastic, and it can fail in a similar fashion and start leaking oil.

Problems With MAF Sensor

Another problem worth noting is the issue with the MAF sensor. The mass airflow sensor on these models also tends to fail at some point.

If you don’t know this sensor monitors the airflow and helps the engine adjust the air-to-fuel mixture. If the sensor is faulty, the car will potentially not run well. And the only way is to replace it.

Water Pump Failures

Water pump failures are also quite common with this engine. The engine has a very sensitive electric water pump that can fail.

Once the water pump fails, the engine can overheat if you don’t detect this problem on time. Replacing the water pump is the only way around it.

Reportedly, engines made between 2012 and 2013 are the ones that are most affected.

Charge Pipe Failure

And the last problem with the N20 engine is infamous, the charge pipe failure. The charge pipe is the pipe that feeds the engine with the compressed air.

Sometimes people tend to crank up the boost levels from the turbocharger to their engine, and when they do, the charge pipe can fail and cause the turbo not to work.

Which Models Have The BMW N20 Engine

The N20 engine was included in the following models:

N20B16

• 2013 – 2016 BMW F10 520i

N20B20

115 kW model

• 2013 – 2016 BMW E89 Z4 sDrive18i
• 2013 – 2017 BMW F25 X3 sDrive18i

135 kW model

• 2012 – 2015 BMW F30 320i
• 2013 – 2016 BMW F34 320i GT
• 2014 – 2016 BMW F32 420i
• 2011 – 2016 BMW F10 520i
• 2013 – 2016 BMW F10 520i
• 2014 – 2016 BMW F22 220i
• 2011 – 2015 BMW E84 X1 xDrive/sDrive20i
• 2011 – 2017 BMW F25 X3 xDrive20i
• 2011 – 2016 BMW E89 Z4 sDrive20i
• 2015 – 2017 Brilliance Huasong 7 MPV

160 kW model

• 2012 – 2017 BMW F20 125i
• 2013 – 2016 BMW F10 525i
• 2015 – 2017 Brilliance Huasong 7 MPV

180 kW model

• 2011 – 2016 BMW F30 328i
• 2014 – 2016 BMW F32 428i
• 2012 – 2016 BMW F10 528i
• 2013 – 2016 BMW F34 328i GT
• 2014 – 2016 BMW F22 228i
• 2014 – 2017 BMW F26 X4 xDrive28i
• 2011 – 2015 BMW E84 X1 xDrive/sDrive28i
• 2016 – 2018 BMW F15 X5 xDrive40e
• 2011 – 2016 BMW E89 Z4 sDrive28i

Conclusion

To sum things up really quickly, the N20 engine is a very problematic engine that is troubled by many issues.

These issues are definitely a good sign for you to shortlist or avoid the engine completely. We say this mainly because of timing chain issues that can be very expensive to fix.

FAQ

What Are The Common Problems Of The BMW N20 Engine?

The N20 engine has a lot of common issues. Namely, timing chain failures are very common. The second problem is probably the oil leaks from the oil filter housing and valve cover. Spark plugs and ignition coils can be a problem as well. On top of all, VANOS actuators can also fail and cause issues.

Is The N20 Engine Reliable?

The short answer is no, the engine is not very reliable. There are many better-built engines out there. If you want to get a better engine, you might be better off purchasing a BMW with an inline-6 engine. Inline-6 engines are what BMW does best. And when you get one, you know that it will be reliable. At least more reliable than the N20.