Do you have a BMW with an N43 engine and are experiencing some issues with it? Are you searching for the reasons, signs, and remedies for these engine mistakes? If yes, then you have landed in the right place since we have got you covered!

We all sometimes face problems with the cars we love or drive out of necessity, but sometimes it’s frustrating because we don’t know how to solve the problems, especially if they are on the engine side and you need to take exemplary care. In this article, I will cover all the information related to the common problems, symptoms, and solutions to fix the issues with the BMW N43 engine. It is a very powerful engine, but not very reliable, so good luck reading this important article.

Introduction

BMW N43 features a 2.0 liter, four-stroke, straight four-cylinder engine. This engine was sold as a naturally aspirated petrol engine from 2007 to 2011. BMW N46 and BMW N45 were precursors of these engines, and BMW N13 is the successor. N43 was not sold in some countries with increased consumption of high-sulfur fuel. So, the productions of its precursors co-existed. Characteristics of the N43B20 engine include an aluminum made robust cylindrical block, four valves in each cylinder, and an aluminium head equipped with a dual overhead camshaft.

Variants of BMW N43 Engines

There were four variants of this engine:

1. N43B16 Engine – 1599 cc – 121 bhp (power) / 160 Nm ( found on the 2007-2009 BMW 1 Series E87 116i / 2008 BMW 3 Series E90 316i )
2. N43B20K0 Engine – 121 bhp (power) at 6,000 rpm and 136.5 ft-lb (torque) at 3,000 rpm
3. N43B20U0 Engine – 148 bhp (power) at 6,000 rpm and 140.2 ft-lb (torque) at 4,250 rpm
4. N43B20O0 Engine – 168 bhp (power) at 6,700 rpm and 155.0 ft-lb (torque) at 4,250 rpm

BMW Models Affected

1. 2007-2009 BMW 1 Series E87 116i
2. 2008 BMW 3 Series E90 316i
3. 2007-2011 BMW 1 Series E81/E87 116i
4. 2007-2011 BMW 3 Series E90/E91/E92/E93 318i
5. 2008-2011 BMW 1 Series E81/E87/E88 118i
6. 2007-2011 BMW 1 Series E81/E82/E87/E88 120i
7. 2007-2011 BMW 3 Series E90/E91/E92/E93 320i
8. 2007-2009 BMW 5 Series E60/E61 520i

No doubt that the BMW N43 engine has outstanding power and torque ratings, but it still has some considerable problems. These engine problems, if not treated and resolved properly, may lead to serious engine issues like engine failure, blowing off the engine, etc.

BMW N43 Engine Issues

The three paramount BMW N43 problems related to its engine are as follows:

1. Timing Chain Issue
2. NOx Sensor Error
3. Fuel Injectors Problems

Let’s dig into the details of BMW N43 engine problems:

1. Timing Chain Issue

Unluckily, the BMW N43 engine can undergo a stretched timing chain problem. Consequently, this issue can wholly destroy and damage your car engine. It may also prevent the car brakes from working appropriately. We recommend a timing chain replacement done to your car to avoid this big problem.

When the BMW N43 timing chain expands, the plastic chain becomes fractured and ultimately drops into the oil pan of the car engine. This shattered plastic chain then gets drawn into the engine oil, and this process leads to the lack of adequate oil pressure. Hence, BMW N43’s low oil pressure either ruins the car engine or clutches the vacuum pump (this vacuum pump provides the braking servo with the vacuity required for a high-performance braking system).

This fault of the BMW N43 engine is comparatively a well-documented one that comes with a repair campaign as well. This repair campaign tests the timing chain for stretching, but it does not guarantee to prevent your vehicle from future failures regarding the timing chain.

What happens during the timing chain snap?

The inlet vents and emission valves strike with the pistons during the BMW N43 timing chain crackle. It results in enormous damage to the N43 engine. At the point of collision with the pistons, the timing chain makes all 16 valves bend. It also causes the rocker arms to shatter, makes the camshaft split, and twists the camshaft housing.

The reason behind the timing chain issue

The timing chain problem is not because of any design-based issues or any mechanical issues with the car engine. These issues are more relatable with long-lasting services such as engine oil changes after every 20,000 miles, BMW N43 low oil pressure, timing chain tensioner, no replacement of timing chain, etc.

These issues can occur if your vehicle has neglected any service or gone late on a service. It may also happen if you take your N43 to a non-specialist garage. The workers there could use an improper and unfitting oil grade during the service, causing catastrophic consequences.

Symptoms

1. Rough idling of your car – the car vibrates or shakes more than the normal routine (it may also happen due to several other vehicle inappropriateness reasons).
2. Unusual noises – weird noises may come out of your vehicle, particularly during rough idling (may also occur when your car looks normal).
3. Engine misfires – the timing chain links the camshaft to the crankshaft, so it becomes snapped due to enough stress and leads to engine misfires.
4. Engine failures – it is most likely to happen that your timing chain gets broken when the car engine does not get started (due to damaged pistons or belts).
5. Metal shavings – it often gives off metal shavings in the engine oil when the timing chain gets snapped.
6. Check engine light – this light gets ON due to several reasons, and a snapped timing chain could be one of these reasons.

Rebuilding of BMW N43 Engine

You might have to rebuild the car engine as it often gets damaged by the timing chain problems. Repairing the car engine is severe, extensive, and intensive labor as the workers have to rebuild it with genuine BMW components. The average cost to rebuild and repair a BMW N43 car engine ranges from $700 to $850.

2. NOx Sensor Error

In 2007, when BMW introduced its N43 and N53 engine series, this well-known brand started incorporating more sophisticated and erudite technology into these models. Some of these latest technologies and developments for BMW include an engine management computer (DME), a variable valve timing technology, and the famous NOx sensors.

What does the NOx sensor do in the BMW N43?

This powerful sensor is present in the exhaust emission system right before the catalytic converter. As the name suggests, this sensor helps measure the level of NOx (Nitrogen Oxides). Moreover, it sends the recorded (measured) data to the engine management computer. Consequently, it makes adjustments in the valve timing and fuel mixture. On the other hand, typical combustion engines lacking this development have the same fuel mixture irrespective of the vehicle conditions. So, it eventually makes them conceded, less effective, and less capable than they could be.

These innovations not only make the N43 and N53 engine series systems produce more power, but they also assist in the burning of less fuel than the withdrawing units. However, these NOx sensors are more likely to get attracted to failures and errors.

Symptoms of BMW N43 NOx sensor error

Here are the chief symptoms of NOx senor failure for BMW N43 engines:

1. Increased fuel consumption – If the sensor fails and shows an error, it cannot receive information from the engine management system. Resultantly, the engine cannot distinguish between the air-to-fuel ratio and fuel mixture. So, it causes the car engine to consider a worst-case scenario and results in the increased consumption of fuel. It happens to guarantee maximum power in miserable conditions.
2. Unstable idling – The failure of NOx sensors can lead the BMW N43 to acquire an unstable engine speed, especially at turnovers.
3. Engine warning lights – One of the reasons behind the active check engine light (or engine warning light) is a failed NOx sensor, so you should check out for it immediately.

Solution for BMW N43 NOx sensor error

There are two possible and effortless solutions for NOx sensor errors. These are as follows:

1. Physical replacement of these sensors.
2. Deleting and clearing the long-term adaptations (make new adaptations instead).

Different errors have different possible solutions, but these two can work for most NOx sensor errors.

3. Fuel Injectors – Problems

Normally, more and more engine-based problems occur as the weather gets colder. It happens because of the arousal of the cold car engine performance. This thing also leads to other gigantic problems, as in BMW N43, it leads to fuel injectors issues.

To your surprise, a failed fuel injector can lead to a wide range of complications, problems, and issues. Furthermore, these problems could lead to catastrophic engine failures if you do not handle them properly.

What do BMW N43 fuel injectors do?

The fuel injector acts as a mechanical pathway between the BMW N43 car engine and its fuel. They work together to power the N43 engine. The BMW N43 will stop and not run without sufficient fuel. So, the car engine loses power during this process, and makes your vehicle stagnant one.

The leaking fuel injector can cause enormous internal damage. If that happens, the car will have difficulty during ignition. Moreover, the oil will get thinner, and there will be odors. The worst that can result if the internal leakage of the fuel injector continues is engine failure. Therefore, we should deal with it nicely. No one wants to put the hood under fire, and for this reason, we highly advise you to check for the maintenance of the fuel injector properly.

Symptoms of faulty fuel injector

1. Stuttered start along with the hiccup sounds – When you turn the keys, the engine will produce a hiccup sound instead of starting.
2. Smoke rising from your car – The smoke usually will arise from the tailpipe. The gas will be gray.
3. Foul odor – This odor is most prevalent during ignition.
4. The gas will be guzzled quicker than normal – One should check the alarming rate as soon as possible since it could be a sign.  
5. Rough drive – The drive would not remain that smooth and perfect.
6. Idling issues – The engine would not operate when reached the peak temperature.  
7. The engine knocks – It will result in uneven burning of fuel. It will burn the fuel instantly all at once.

Solution for fuel injector issues

The only solution is the replacement of the fuel injector. It will enable you to have a smooth drive, and the fuel economy and efficiency will get enhanced. On replacing, the ignition will get smooth and perfect, and the odor will be non-existent.

Conclusion

BMW N43 is an exceptional car engine, but there are some problems that one has to face. If you are considering purchasing it, prepare yourself for facing these issues. Also, look up for solutions to deal with them. But… with proper maintenance, you will be able to enjoy the performance of this engine for a very long time.