BMW B38 / B37 vs BMW M54: which engine is more reliable?

According to our risk index, the BMW B38 / B37 carries less risk than the BMW M54: 20/100 (low risk) versus 54/100 (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 BMW M54 has 2 documented serious faults, the main one being «Thermostat and water pump failure».

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

Risk index

BMW M54

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 202614 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 BMW M54 reliable?

The BMW M54 (2000-2006) is a naturally aspirated petrol inline-six with a reputation for longevity, passing 200,000 km if maintained. Its weak points are the crankcase ventilation valve and the plastic cooling system; check that they have been renewed.^[4][5][6]

See the 5 of the BMW M54 faults

Side-by-side comparison

Comparison of BMW B38 / B37 and BMW M54
Item	BMW B38 / B37	BMW M54
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,499 cm³	—
Timing	Chain	Chain
Power	75–231 hp	170–235 hp
Production	since 2014^[7][8][9]	2000–2006^[10][11]
Reliability
Risk index (what is it?)	20Low risk	54High risk
Documented faults	3	5
Of high or critical severity	1	2
Worst severity	Critical severity	High 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	High severity: Thermostat and water pump failure High severity: Cracked expansion tank and coolant leak Medium severity: Cracked crankcase ventilation valve (CCV) and oil consumption
Most expensive documented repair	No reliable data	No reliable data
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^[12] B37TÜ1 1.5 diesel 95-116 hp (from late 2017)^[13]	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)^[14]	M54B22, 2.2 litres (168-170 hp)^[4][5][6] M54B25, 2.5 litres (189-192 hp)^[4][5][6] M54B30, 3.0 litres (228-235 hp)^[4][5][6]
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 16 models with the BMW B38 / B37

BMW M54

Other comparisons

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With the BMW M54

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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
BMW M54 Engine Guide: Reliability, Common Problems & Tuning PotentialEuro Premium Parts · Technical documentation · consulted 5 October 2026
Il motore da 6 cilindri che supera agilmente i 300.000 kmAutoblog.it · Motoring press · published 13 February 2026 · consulted 5 October 2026 · in Italian
BMW M54 reliabilityAutoscore · Other source · 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
BMW M54Wikipedia (inglés) · Other source · consulted 5 October 2026
BMW M54Wikipedia (alemán) · Other source · consulted 5 October 2026 · in German
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