Turbochargers on 3-cylinder BMW 1 Series engines such as the 116i and 118i regularly show wear. Internal faults and incorrect calibration of the wastegate (a valve that controls the turbo pressure) are common causes. Early inspection prevents power loss and expensive engine damage. Read on to discover which symptoms you need to recognise and how to solve problems before the situation gets worse.
Recognising the symptoms of a faulty turbo
A failed turbocharger gives off clear signals. Loss of power is the most common problem: your car switches into limp mode (a safety mode in which the engine limits its power) due to insufficient boost pressure (the pressure the turbocharger builds up in the intake system). This mainly happens after starting or after recent repairs. Acceleration feels sluggish and the engine does not respond the way you are used to.
Unusual noises also point to turbo problems. Listen for high-pitched, whistling or shrieking sounds when accelerating. This indicates damaged bearings or blades in the turbo. Some owners report a rattling noise on a cold start. This is then followed by unstable running and temporary loss of power.
Other symptoms are:
- Blue or black smoke from the exhaust due to oil leaking into the combustion chamber
- Check engine light that comes on with fault codes such as 123401, 123412, 123432 or 123437
- Visible coolant leaks under the turbo, often confused with head gasket problems
- Sudden loss of power under high load, such as when driving at full throttle
‘ Owners who do not change the oil regularly run the highest risk of this type of damage. ’
What causes turbocharger problems on the BMW 1 Series
On BMW 1 Series models with the B38 engine (a compact 3-cylinder turbocharged petrol engine) faults arise from various causes. The F20 and F21 generation (internal BMW type codes for the first- and second-generation 1 Series from 2011–2019) are known for this. Misalignment of the wastegate actuator is a common problem. After repairs to the cooling system or after fitting a new turbo, air bubbles can occur. These interfere with the automatic calibration. As a result, the wastegate moves out of position and the turbo no longer delivers any boost.
Contaminated oil or low oil level leads to overheating and seizing bearings. Dirty oil clogs the narrow channels in the turbo, causing lubrication to be insufficient. Owners who do not change the oil regularly run the highest risk of this type of damage.
Coolant leaks occur mainly with water-cooled turbos. The 118i uses this type of turbo. These leaks cause a pressure loss of up to 1.5 bar without always leaving visible external traces. A pressure test is therefore necessary to distinguish the problem from a faulty head gasket.
Other causes are:
- Boost leaks or blockages in the intake or exhaust, forcing the turbo to work harder
- Non-OEM parts (non-original manufacturer components) that wear out more quickly
- Aggressive driving without a cool-down period after intensive use
How to test whether the turbo is faulty
Start by reading out fault codes using dealer software or a good OBD scanner. Pay particular attention to detailed information about the wastegate position. The tolerance must be less than 2 mm, ideally 0 mm. With greater deviations, the wastegate is probably incorrectly adjusted.
Carry out a pressure test on the cooling system at 1.5 bar. This shows whether there are coolant leaks in or around the turbo. For the wastegate actuator you can use a vacuum pump. Test at 13 mm Hg whether the rod moves as expected. On the F20 and F21 models this is relatively easy to do.
Visually inspect the turbo for oil traces, coolant under the unit and play in the rod. Also look for movement in the turbine shaft. A lot of play indicates worn bearings. If in doubt, remove the exhaust side of the turbo to check for internal leaks.
Costs of turbocharger replacement and repair
A complete turbo replacement on the BMW 1 Series quickly costs from around €2,000, depending on the type of turbo and labour costs. Always use OEM parts (original manufacturer parts) or high-quality alternatives to prevent problems after installation.
Fortunately, replacement is not always necessary. Wastegate calibration often costs little and solves many problems. Some specialists can correct the rod and recalibrate it, saving thousands of euros. Replacing seals or damaged blades is an intermediate option with moderate costs.
Always ask for a diagnosis from a BMW specialist first. Many dealers immediately recommend a full replacement, whereas a targeted repair is often sufficient. Check forums and experiences from other owners to find reliable garages that focus on accurate diagnosis.
‘ Dirty oil is the main cause of turbo failures on 3-cylinder engines. ’
Prevent future turbo problems with proper maintenance
Change the oil every 10,000 kilometres, using high-quality engine oil that meets BMW specifications. Dirty oil is the main cause of turbo failures on 3-cylinder engines.
After driving hard, give the turbo 1 to 2 minutes to cool down before switching off the engine. This cool-down period stabilises the oil and coolant temperature and prevents the bearings from overheating. This particularly applies after track days (special events where you can drive on a circuit) or long journeys on the motorway.
Schedule regular turbo inspections during services. Have the garage check for unusual noises, play in the shaft and leaks. Use only OEM parts for repairs to ensure the longest possible service life of the turbo.
Extra tips:
- Monitor smoke and power delivery while driving
- Test the wastegate actuator with a vacuum pump if in doubt
- Avoid prolonged high boost without proper maintenance
- Do not drive at full throttle straight after a cold start
When to go to a garage with turbo problems
Go to a garage immediately if you experience loss of power in combination with fault codes or limp mode. This points to boost pressure problems which, if not repaired, will lead to engine damage. Whistling or high-pitched noises also require swift action, as damaged bearings deteriorate rapidly.
Visible smoke from the exhaust, especially blue smoke, means that oil is entering the combustion chamber. This requires an immediate diagnosis. Coolant leaks under the turbo should likewise not be ignored, as they lead to overheating.
If in doubt, always have a pressure test and fault-code read-out carried out. Many problems can be solved with targeted calibration or small repairs, but delaying only makes the damage worse. Choose a garage with experience in BMW engines and turbo diagnostics for the best result.
Discover more about your BMW
On the Carnews website you will find more information about maintenance, common problems and practical tips for BMW models. You can read about engine problems, maintenance costs and the experiences of other owners.
Frequently asked questions
The most common symptoms are noticeable loss of power and sluggish acceleration, often accompanied by limp mode. In addition, you often hear a whistling, high-pitched or rattling noise when accelerating. Blue or black smoke from the exhaust and an illuminated engine warning light with associated fault codes are also very common. Sometimes there are also visible coolant leaks around the turbo.
Premature wear or failure of the turbocharger on BMW 1 Series models is mainly caused by contaminated or low oil, which overheats and seizes the bearings. In addition, coolant leaks and problems in the cooling system play a role, because the turbo is then insufficiently cooled. Misalignment or incorrect calibration of the wastegate actuator can also lead to too little or incorrect turbo pressure and extra wear. Furthermore, boost leaks, poor (non-OEM) parts and an aggressive driving style without a cool-down period can significantly shorten the life of the turbo.
In the event of a turbocharger failure in a BMW 1 Series, costs range roughly from a relatively inexpensive wastegate adjustment or calibration (a few hundred euros) to a complete turbo replacement, which can quickly approach or exceed €2,000. Intermediate options include overhauling the turbo, such as replacing seals and any damaged blades, which usually falls in the mid-price category. It is often worthwhile first to have the wastegate actuator, vacuum and cooling circuits and oil contamination checked, because correct adjustment or a minor repair can sometimes eliminate the need for a new turbo. Ideally, have the diagnosis carried out by a BMW specialist with experience of the B38 engine and 1 Series turbos.
Change the engine oil in your BMW 1 Series every 10,000 km using high-quality, BMW-approved oil and use only OEM filters and parts. At every service, have the turbo, hoses and wastegate actuator visually checked for oil traces, leaks and play. Avoid prolonged high loads on a cold engine and, after hard or fast driving, let the engine idle for 1–2 minutes so that the turbo can cool down. Be proactive in watching for loss of power, strange whistling or rattling noises and smoke, and if you notice these signs, have a BMW specialist carry out a diagnosis immediately to prevent consequential damage.
Yes, in particular the BMW 1 Series F20/F21 with the three-cylinder B38 petrol engine (such as the 114i, 116i and 118i) is relatively often mentioned in connection with turbocharger and wastegate problems. On these model years/engines, misalignment of the wastegate actuator, coolant leaks around the water-cooled turbo and oil contamination play a major role. This regularly leads to fault codes, limp mode and loss of power. Other 1 Series engines can also suffer turbo failures, but in practice the B38 variants are mentioned strikingly often.
