BMW B38 / B37 vs 1.8 T 20v: which engine is more reliable?

According to our risk index, the BMW B38 / B37 carries less risk than the 1.8 T 20v: 20/100 (low risk) versus 32/100 (moderate risk). The BMW B38 / B37 has 1 documented serious fault, the main one being «B38 crankshaft thrust bearing failure (units before April 2015)»; the 1.8 T 20v has 1 documented serious fault, the main one being «Turbo wear and oil consumption».

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

Risk index

1.8 T 20v

Moderate risk · 1 serious fault

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

Reviewed on 30 October 202619 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 1.8 T 20v reliable?

With up-to-date maintenance, the 20-valve 1.8T has a reputation as a powerful, durable engine for its time, but owner reports document recurring faults: ignition coils (especially on 2001 to 2003 units), water pump and air mass meter, and less often the turbo -sometimes linked to growing oil consumption- and the timing chain tensioner.^{[4][5][6][7][8][9]}

See the 5 of the 1.8 T 20v faults

Side-by-side comparison

Comparison of BMW B38 / B37 and 1.8 T 20v
Item	BMW B38 / B37	1.8 T 20v
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,499 cm³	1,781 cm³
Timing	Chain	Timing belt (dry)
Power	75–231 hp	150–225 hp
Production	since 2014^[10][11][12]	1996–2006^{[13][14][15][16]}
Reliability
Risk index (what is it?)	20Low risk	32Moderate risk
Documented faults	3	5
Of high or critical severity	1	1
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: Turbo wear and oil consumption Medium severity: Water pump failure Medium severity: Timing chain tensioner noise and wear
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^[17] B37TÜ1 1.5 diesel 95-116 hp (from late 2017)^[18]	None
With cautionVersions to be cautious about	B38 1.2 (B38A12, MINI One)^[11] B38 1.5 136 hp up to April 2015 (B38A15)^[1] B38K15T0 231 hp (BMW i8)^[19]	1.8 T 20v 150 hp (AEB/AGU/ARZ/AUM, 1996-2005)^[5][9] 1.8 T 20v 180 hp (AUQ, 1998-2006)^[6][7] 1.8 T 20v 225 hp quattro (BAM, 1999-2006)^[7]
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

1.8 T 20v

See the 11 models with the 1.8 T 20v

Other comparisons

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With the 1.8 T 20v

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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
Fiabilité et pannes Volkswagen Golf IVFiches-auto.fr · Other source · consulted 27 September 2026 · in French
Fiabilité et pannes Volkswagen PassatFiches-auto.fr · Other source · consulted 27 September 2026 · in French
Fiabilité et pannes Audi A3Fiches-auto.fr · Other source · consulted 27 September 2026 · in French
Fiabilité et pannes Audi TTFiches-auto.fr · Other source · consulted 27 September 2026 · in French
Fiabilité et pannes Seat LeónFiches-auto.fr · Other source · consulted 27 September 2026 · in French
Seat Leon Mk1: Probleme, Schwachstellen, ErfahrungenGebrauchtwagenberater.de · Other source · consulted 27 September 2026 · in German
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
List of Volkswagen Group petrol enginesWikipedia · Other source · consulted 27 September 2026
Audi TTWikipedia · Other source · consulted 27 September 2026
SEAT LeónWikipedia · Other source · consulted 27 September 2026
SEAT ToledoWikipedia · Other source · consulted 27 September 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