BMW B48 (B48A20 / B48B20) / B38 (B38A15 / B38B15)Timing chain
Timing chain on the early units (2014-2018), redesigned in the B48TU on the BMW B48 / B38
We have found no documented cases of timing chain breakage on the B48. The one concrete fact that does exist is that BMW redesigned the chain as a single piece in the 2018 B48TU update, which points to an area for improvement in engines built before that date.[1]
Why this rating?
High severity: Risk of a serious engine, turbo or gearbox failure.
Frequency rare: Unlike earlier BMW engines (such as the N47 diesel or the N20 petrol engine itself), we have found no lawsuits, campaigns or forums with a significant volume of chain failure cases on the B48. The only concrete evidence is BMW's own design revision in 2018 (one-piece chain). As a precaution, and following the same criterion we apply to other engines on this site, we do not raise the frequency because of a simple design improvement with no documented failures behind it: we rate it as rare.[1]
Symptoms
- On any engine with a timing chain, a metallic rattle in the first seconds after a cold start is the classic warning sign; we have found no documented cases of this symptom reported specifically for the B48.[1]Chain noise: other faults that cause it · Garage soon
- On any engine with a timing chain, a metallic rattle in the first seconds after a cold start is the classic warning sign; we have found no documented cases of this symptom reported specifically for the B48.[1]Noise on start-up: other faults that cause it · Garage soon
Why it happens
Wikipedia records that the 2018 B48TU technical update introduced a one-piece timing chain, compared with the previous design; it does not detail what specific problem prompted the change.[1]
Affected cars and years
The B48TU update, with a one-piece chain, arrived in 2018; for that reason we place the period of greatest caution between the start of production (2014) and that date, although we have no specific failure cases that confirm it.[1]
| Version | Years | Codes |
|---|---|---|
| B38 1.5 136 hp (MINI Cooper, 118i) | since 2014 | B38A15B38B15 |
| B48 2.0 178-197 hp (120i, 220i, 320i, 520i, X1/X2/X3 20i, MINI Cooper S) | since 2014 | B48A20B48B20 |
| B48 2.0 252-258 hp (330i, 530i, X3/X4 xDrive30i) | since 2015 | B48A20B48B20 |
| B48 2.0 up to 302-312 hp, high performance (MINI John Cooper Works, BMW X1 M35i) | since 2015 | B48A20B48C20 |
Models fitted with the affected versions
BMW
- BMW Serie 1 F202015–2019
- BMW Serie 2 F222015–2021
- BMW Serie 2 Active Tourer F452015–2021
- BMW Serie 3 F302015–2019
- BMW Serie 5 F102016–2017
- BMW Serie 5 G302017–2023
- BMW X1 F482015–2022
- BMW X2 F392018–2023
- BMW X3 F252014–2017
- BMW X3 G012017–2024
MINI
- MINI Cooper F562014–2024
- MINI Countryman F602017–2023
- MINI Cooper F552014–2024
How much it costs to repair
Includes: Replacement of the chain, guide and tensioner if wear is found, with partial removal of the front of the engine.[1]
We have found no published cases or quotes for this repair on the B48; we include this fault because of BMW's 2018 design revision, not because of documented complaints.
Prices in Spain, including VAT. A workshop hour costs on average €38–66 at independent garages and €77–134 at dealerships in Spain, depending on the region and the brand. How we calculate costs
How to check for it before buying a used car
- Start the engine from cold and listen to the first few seconds: a metallic rattle would be the typical warning sign of a slack chain, although there are no documented cases of it on the B48.[1]
Parts needed
The part or kit that fixes this fault, according to the sources.
Timing chain kit (chain, guide and tensioner)
Replaces the original components if wear or abnormal noise is found.
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How to prevent it
- Stick to the oil change intervals recommended by BMW: degraded oil speeds up wear on any chain tensioner.
Recalls, campaigns and claims
As of 27 September 2026, we have no record of recalls, campaigns or extended manufacturer warranties for this fault. Check with an official dealer using the chassis (VIN) number: they will tell you whether the car has any outstanding campaign.
What owners say
Frequently asked questions
Does the BMW B48 timing chain fail?
We have found no documented cases of breakage. The objective fact is that BMW redesigned the chain as a single piece in the 2018 B48TU update, which suggests an improvement on the earlier design, not a confirmed mass failure.[1]
What did BMW change in 2018 with the B48TU?
It introduced a one-piece timing chain, separate cooling circuits, forged internal components and an updated Bosch injection system.[1]
Should I be worried if I buy a pre-2018 B48?
There is no evidence of a widespread fault, so it is no reason to rule the car out; as with any chain-driven engine, checking the cold start and the service history is a reasonable precaution.[1]
What can you do now?
We will put you in touch with a partner only if you authorise it in the form.
Other BMW B48 / B38 faults
- Medium severityFrequency: OccasionalCoolingDeterioration of hoses and seals in the cooling circuit, with coolant lossYes: over the years and many heat cycles, the hoses, the expansion tank and some of the plastic seals in the B48/B38 cooling circuit can deteriorate and lose coolant, sometimes without any visible puddle under the car.
- Medium severityFrequency: OccasionalLubricationOil leaks or seepage from seals and covers, near the turbo and the VANOSYes: over time, oil seepage or leaks can appear at seals, covers and crankcase ventilation connections, in an area of the engine close to the turbo and the VANOS system.
- Low severityFrequency: CommonIntakeCarbon build-up on the intake valves (direct injection)Yes, as on most direct-injection engines: because they are not washed by fuel, the intake valves on the B48/B38 build up carbon over the years, especially in urban use, with a loss of smoothness and a less stable idle.
More faults with the timing chain on other engines and cars
- Critical severityFrequency: Very frequent1.5 BlueHDiWear and breakage of the 7 mm chain between the camshaftsIn 1.5 BlueHDi engines built between October 2017 and January 2023, the 7 mm chain linking the camshafts can stretch and break, causing serious engine damage. Stellantis has recalled them and covers the fault for 10 years or 240,000 km.Repair (garage): €730–€820
- Critical severityFrequency: Very frequent1.2 and 1.4 TSITiming chain stretch and tensioner failure (EA111)On the 1.2 and 1.4 TSI EA111 (2006-2015) the chain can stretch and the tensioner fall short; if the chain jumps a tooth, the valves hit the pistons. Volkswagen admitted the defect in 2012 and revised the chain and tensioner between 2010 and 2011.Repair (garage): €700–€1,400Appears at around 30,000 km
- Critical severityFrequency: Very frequentBMW N47Rear timing chain stretch and breakageYes: the N47 has its timing chain at the rear of the engine, next to the gearbox, and on a very high proportion of units, especially those built between 2007 and 2009, it stretches or breaks prematurely because of an inadequate tensioner, with a risk of destroying the engine.Repair (garage): €1,590–€3,000Appears at around 50,000 km
- Critical severityFrequency: Very frequentOM651Timing chain stretch and tensioner failureYes: the OM651 timing chain can stretch prematurely, above all on units built up to 2013, and in 2014-2015 Mercedes-Benz recalled around 114,000 vehicles in Germany over a defective sealing ring in the tensioner. A metallic rattle on a cold start is the first sign.Repair (garage): €2,000–€3,500Appears at around 120,000 km
- Critical severityFrequency: Very frequent2.0 Ingenium diéselTiming chain stretchYes: the timing chain on the 2.0 Ingenium diesel can slip or stretch prematurely and put the engine out of time, with a risk of serious failure. It is documented on the Evoque, Discovery Sport, XE, E-Pace and F-Pace, with engine failures between 90,000 and 130,000 km in several owner reports.Repair (garage): €4,000–€7,000Appears at around 90,000 km
- Critical severityFrequency: Common1.3 MultijetTiming chain stretch and tensioner failureYes: the timing chain's hydraulic tensioner can lose pressure and let the chain slacken; if it skips teeth or breaks, it can destroy the engine. It is a documented problem on Fiat, Opel, Suzuki and Ford cars with this engine, mainly linked to long oil change intervals.Repair (garage): €350–€550Appears at around 70,000 km
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Sources
Every fact on this page links to its source. If you find an error, let us know.
- BMW B48Wikipedia (inglés) · Other source · consulted 27 September 2026