Which BMW Has the B38TU Engine? Full Model List Explained
Image: BMW B38A15P Complete Engine for Sale at MT Auto Parts for £2,799.99
The BMW B38 engine is the 1.5-litre three-cylinder engine you will find in the smaller end of BMW's range: the 1, 2 Series Active Tourer, X1, and a handful of other BMW models. It is not the engine that tends to grab headlines, but there are a lot of them on UK roads, and if you are buying a used BMW in this part of the range, you will almost certainly encounter one.
This guide answers the question that comes up most often: which BMW actually has the B38 engine, and specifically the updated B38TU version? It also covers what you need to know about reliability and what to check before buying, explained simply.
What Is the BMW B38 Engine?
Simply put, the B38 is BMW's three-cylinder petrol engine. It is 1.5 litres, turbocharged, and sits at the bottom of BMW's modern engine family, the same family that includes the B48 four-cylinder and B58 six-cylinder, just with one fewer pot.
Three cylinders sounds unusual for a BMW, and when the engine first appeared in 2014 it raised a few eyebrows. But it makes sense when you understand where it goes. The compact front-wheel-drive models in BMW's range, the 1 Series F40, the 2 Series Active Tourer, the X1, need an engine that fits sideways across a relatively tight engine bay. Three cylinders take up less space than four, which is why this engine exists.
On the road it is a fairly willing unit. You get 109hp in base trim or 136 to 140hp in higher states of tune. It is not fast by BMW standards, but it is economical, responsive enough for everyday driving, and significantly better than its predecessor, the N13.
What does B38TU mean?
TU stands for Technical Update. BMW used this suffix to mark a revised, improved version of the original B38. The B38TU arrived from around 2016 onwards and fixed the main problems that had been reported on the original engine.
The most important change was to the cooling system. On the original B38, the turbocharger housing was water-cooled and built into the exhaust manifold. That arrangement was prone to cracking from the constant heat cycling, which caused coolant leaks and, in some cases, overheating. The B38TU redesigned this area. The timing chain tensioner was also revised. The original one wore faster than it should have. Both of these changes make the B38TU a noticeably more dependable engine than what came before it.
If you are buying a used BMW with a B38 engine, it is worth confirming whether it has the original or the TU version. You can do this by checking the full engine code on the block, or by entering your VIN on RealOEM.com. Cars built from 2016 onwards generally have the B38TU.
Which BMWs Have the B38 Engine? Full Model List
BMW 1 Series
The B38 engine replaced the older N13 in the F20 1 Series from 2015. If you have a 116i or 118i F20 built after that date, it almost certainly has a B38. All F40 1 Series models in 116i and 118i trim use the B38TU throughout the generation.
BMW 2 Series Active Tourer and Gran Tourer
The F45 Active Tourer and F46 Gran Tourer are probably where the B38 is most common in the UK. Both 216i and 218i variants use it across the full production run.
BMW 2 Series Gran Coupé and second-generation Active Tourer
The F44 Gran Coupé and the newer U06 Active Tourer (from 2022) also use the B38 in lower-powered petrol trim.
BMW 3 Series
The B38 had a brief and relatively uncommon appearance in the 3 Series. The 318i in F30 saloon and F31 Touring form used it from 2015 to 2019. You do not see many of these. It was not a popular specification in the UK, but they exist.
BMW X1
Both generations of the X1 use the B38 in sDrive18i form. The current U11 X1 (from 2022) also uses a version of it in the plug-in hybrid 25e model, combined with an electric motor.
BMW X2
The X2 in sDrive18i specification uses the B38 across both the F39 first generation and the U10 second generation.
Is the BMW B38 Engine Reliable?
The honest answer is: yes, if it has been looked after. The B38 shares the same basic engineering as the four-cylinder BMW B48 engine, same architecture, same front-mounted timing chain, same approach to turbocharged petrol direct injection. Most well-maintained examples reach 100,000 miles without any major trouble.
The engines that develop problems early are almost always ones where oil changes were left too long, the car was used mainly for short trips without getting properly up to temperature, or early warning signs were ignored. Keep on top of the oil and the B38 tends to be straightforward.
That said, there are a few things specific to this engine that are worth knowing about.
The vibration — it is normal, not a fault
The first thing many B38 owners notice is that the engine feels busier and more vibey than a four-cylinder at idle. This is simply what three cylinders feel like. BMW manages it with a balance shaft and specific engine mounts, but it is still perceptibly rougher than the B48 at tickover. It is not something going wrong. It is just the character of a three-pot engine.
What you do not want is the vibration getting noticeably worse over time, which usually means the engine mounts have worn and hardened. Worn mounts are a common and relatively affordable fix — but they are one of the first things to check on a B38-powered car that feels rougher than expected.
Cooling system — especially on pre-2016 cars
This is the main reliability concern on the original B38, and the primary reason the B38TU update was introduced. The original engine had the turbocharger housing water-cooled and integrated with the exhaust manifold. That area cracks from the constant heat changes, leading to coolant leaks.
On any original B38, roughly pre-2016, keep a close eye on the coolant level, check the colour of the coolant in the expansion tank, and look at the oil cap for any milky residue. The B38TU improved this significantly, but if you are buying an older example, this is the area to focus on.
Timing chain tensioner — cold start rattle
The original B38 timing chain tensioner wore faster than it should. On affected cars, you will hear a rattle from the engine for the first 20 to 30 seconds after a cold start, which then clears as oil pressure builds. If you hear this on a car you are test driving, do not ignore it; It should be investigated.
The good news compared to something like an N47 diesel is that the B38's chain is at the front of the engine. That means any chain or tensioner work is considerably more accessible and therefore less expensive. It is not the same level of concern as a rear-mounted chain job.
Carbon buildup on the valves
This affects all direct injection engines, not just the B38. Because fuel is injected directly into the cylinder rather than past the intake valves, the valves do not get washed with petrol on every stroke. Over time, carbon builds up on them, particularly on cars used mostly for short journeys in town. The symptoms are a rough idle, hesitation under light throttle, and occasional misfires.
A walnut blast clean of the intake valves at around 60,000 to 80,000 miles is the standard fix. It is a workshop job but not a particularly alarming one.
Water pump and thermostat
The B38 uses a mechanically driven water pump rather than an electric one, which is actually a point in its favour. Electric pumps can fail suddenly, whereas mechanical ones tend to give more warning. That said, water pump and thermostat replacement is standard preventative maintenance on any B38 approaching 70,000 to 80,000 miles.
On original B38 engines built before 2016, inspect the area around the BMW turbocharger and exhaust manifold for any coolant staining or residue. This is the most likely place to find a problem, and it is the fault most often missed by previous owners who do not know what to look for.
What to Check Before Buying a Used Car with the B38 Engine
Whether it is a 1 Series, 2 Series Active Tourer, X1, or anything else on the list above, run through these checks before handing over any money.
Service history. This matters more than anything else on a B38. You want to see oil changes every 6,000 to 9,000 miles rather than the BMW CBS schedule interval, which most specialists consider too long for a turbocharged engine. A car with consistent, short oil change intervals in its history is a very different proposition from one that has been left to the dashboard reminder.
Cold start test. Always start the car from fully cold. Listen for any rattling noise from the engine in the first 30 seconds. It should settle quickly if present at all. Persistent rattling, or rattling that takes more than a few seconds to clear, points to timing chain tensioner wear and needs proper investigation before you buy.
Coolant condition. Check the expansion tank. The coolant should be clean and the correct colour for the type used. Brown or rusty coolant suggests overheating history or a long time since it was changed. Check the oil filler cap on the top of the engine for any white or milky residue, which would indicate coolant mixing with the oil.
Engine mounts. With the engine running, look at it from the engine bay. There should be minimal movement. Excessive rocking under blips of the throttle suggests the mounts are gone. Worth checking on any car over 60,000 miles.
Diagnostic scan. Any independent BMW specialist can run a full scan in around 15 minutes. It picks up stored fault codes that will not necessarily trigger a warning light on the dashboard but can tell you a lot about what the engine has been up to, fuel pressure, boost, coolant temperature faults, and more.
MT Auto Parts stocks genuine used BMW B38 engines for F- and G-generation models, with confirmed donor mileage, full engine code, and a 30-day warranty on every unit (T&C apply). We break BMW only, so when you enquire about a B38 engine, the team can confirm the exact code, whether it is the TU variant, and whether it is the right fit for your specific car before anything is dispatched. Over 15,000 five-star reviews. 24 to 48 hours delivery across the UK. Browse at mtautoparts.com or send your registration on WhatsApp.
Frequently Asked Questions
Is the BMW B38 engine reliable?
Yes, generally. A well-maintained B38 typically reaches 100,000 miles without serious issues. The engines that give trouble are almost always ones with extended oil change intervals or cooling system problems that were left unattended. The B38TU update addressed the main weak points of the original.
What is the difference between the B38 and B38TU?
The B38TU is the updated version introduced from around 2016. The main improvements were to the turbocharger cooling arrangement, which was prone to cracking on the original, and the timing chain tensioner, which wore prematurely on earlier engines. If you have a choice, the B38TU is the one to go for.
Which BMW 1 Series has the B38 engine?
The F20 1 Series 116i and 118i from 2015 to 2019, and the entire F40 1 Series in 116i and 118i trim from 2019 to 2024. The M135i in F40 form uses a B48 four-cylinder, not the B38.
How long does a BMW B38 engine last?
Between 100,000 and 140,000 miles is a reasonable expectation for a well-maintained example. Some go well beyond that. The main factors are how frequently the oil was changed and whether the cooling system was kept in good order.
Does the BMW B38 have timing chain problems?
The original B38 had a timing chain tensioner that wore quicker than expected, causing a cold-start rattle. This was improved in the B38TU update. The chain itself is front-mounted, which makes any necessary work considerably more accessible and less expensive than the rear-mounted chain on something like the N47 diesel.
Is it worth buying a used BMW with the B38 engine?
Yes, provided the service history stacks up, and the cooling system is in good order. The B38TU in particular is a sound used buy. The three-cylinder character at idle takes some getting used to, but on the road it is a capable and economical engine that is cheaper to run and maintain than the larger four-cylinder alternatives.
Disclaimer: This article covers the BMW B38 engine family including B38TU variants. Fault patterns and reliability information are based on widely reported owner and independent workshop experience. Always consult a qualified BMW specialist before making decisions about engine purchase or repair.
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