BMW B38 / B37 vs 2.3 MZR DISI Turbo: which engine is more reliable?

According to our risk index, the BMW B38 / B37 carries less risk than the 2.3 MZR DISI Turbo: 20/100 (low risk) versus 63/100 (high risk). The BMW B38 / B37 has 1 documented serious fault, the main one being «B38 crankshaft thrust bearing failure (units before April 2015)»; the 2.3 MZR DISI Turbo has 2 documented serious faults, the main one being «Timing chain stretch and VVT actuator failure on the 2.3 DISI Turbo».

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

Risk index

2.3 MZR DISI Turbo

High risk · 2 serious faults

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

Reviewed on 30 October 202613 sources How we work

Is the BMW B38 / B37 reliable?

BMW and MINI's three-cylinder B38 (petrol) and B37 (diesel) have no serious, widespread documented fault. The only problem reported in the press is the crankshaft thrust bearing on early B38 units (up to April 2015), corrected by BMW. BMW's EGR campaigns affect four- and six-cylinder diesels, not the B37.^[1][2][3]

See the 3 of the BMW B38 / B37 faults

Is the 2.3 MZR DISI Turbo reliable?

Mazda's 2.3 DISI Turbo (L3-VDT, 2005-2013) is powerful but demanding: the timing chain, the turbo and oil sludge are its weak points; only buy one with a good oil service history.^[4][5][6]

See the 3 of the 2.3 MZR DISI Turbo faults

Side-by-side comparison

Comparison of BMW B38 / B37 and 2.3 MZR DISI Turbo
Item	BMW B38 / B37	2.3 MZR DISI Turbo
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,499 cm³	2,261 cm³
Timing	Chain	Chain
Power	75–231 hp	256–263 hp
Production	since 2014^[7][8][9]	2005–2013^[4][10]
Reliability
Risk index (what is it?)	20Low risk	63High risk
Documented faults	3	3
Of high or critical severity	1	2
Worst severity	Critical severity	Critical severity
Main faults	Critical severity: B38 crankshaft thrust bearing failure (units before April 2015) Medium severity: Coolant leaks and water pump or thermostat failure on the B38 Low severity: Carbon build-up on the B38's intake valves and injectors	Critical severity: Timing chain stretch and VVT actuator failure on the 2.3 DISI Turbo High severity: Premature turbocharger wear from poor lubrication on the 2.3 DISI Turbo Medium severity: Oil consumption and sludge in the 2.3 DISI Turbo engine
Most expensive documented repair	No reliable data	up to €2,200Premature turbocharger wear from poor lubrication on the 2.3 DISI TurboPublished figure^[5]
Which versions to buy
BuyRecommended versions	B38 1.5 136-140 hp from April 2015 (B38A15 / B38B15)^[1] B37 1.5 diesel 95-116 hp (B37C15K0 / B37C15U0), up to 2017^[11] B37TÜ1 1.5 diesel 95-116 hp (from late 2017)^[12]	None
With cautionVersions to be cautious about	B38 1.2 (B38A12, MINI One)^[8] B38 1.5 136 hp up to April 2015 (B38A15)^[1] B38K15T0 231 hp (BMW i8)^[13]	2.3 MZR DISI Turbo 256-260 hp (L3-VDT, 2005-2009)^[4][5] 2.3 MZR DISI Turbo (L3-VDT, 2010-2013)^[4][5]
AvoidVersions to avoid	None	None

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

BMW B38 / B37

See the 14 models with the BMW B38 / B37

2.3 MZR DISI Turbo

Other comparisons

With the BMW B38 / B37

With the 2.3 MZR DISI Turbo

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Sources

Every fact on this page links to its source. If you find an error, let us know.

BMW Dreizylinder: Dauertest-Probleme des B38 behoben?BimmerToday · Motoring press · published 5 October 2017 · consulted 4 October 2026 · in German
2024: BMW recall due to EGR coolers extended againcar-recalls.eu · Motoring press · published 28 March 2024 · consulted 4 October 2026
BMW diésel Europa: llamada a revisión por el EGR y riesgo de incendioDiariomotor · Motoring press · consulted 4 October 2026 · in Spanish
Mazda L engineWikipedia (inglés) · Other source · consulted 5 October 2026
Problemas Mazda CX-7Totalrenting · Other source · consulted 5 October 2026 · in Spanish
2009 Mazda CX-7 engine problemsCarComplaints · Owners' forum · consulted 5 October 2026
BMW B38 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026
BMW B38 (Wikipedia, alemán)Wikipedia · Other source · consulted 4 October 2026 · in German
BMW B37 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026
Mazda CX-7Wikipedia (inglés) · Other source · consulted 5 October 2026
Project one M: MINI Cooper D F56 fährt eine Million Kilometer in 12 JahrenBimmerToday · Motoring press · published 24 June 2026 · consulted 4 October 2026 · in German
BMW Baukasten-Diesel: Mehr Infos zur TÜ1 für B47 und B37BimmerToday · Motoring press · published 20 November 2017 · consulted 4 October 2026 · in German
BMW i8 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026