BMW B38 / B37 vs Skyactiv-G: which engine is more reliable?

According to our risk index, the BMW B38 / B37 carries less risk than the Skyactiv-G: 20/100 (low risk) versus 25/100 (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 Skyactiv-G has no documented serious faults.

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

Risk index

Skyactiv-G

Moderate risk · 0 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 202616 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 Skyactiv-G reliable?

The Skyactiv-G is a naturally aspirated petrol engine that the German specialist press consistently describes as reliable, with no documented pattern of serious engine faults in any Mazda model reviewed. Its weak point, shared with almost any direct-injection petrol engine, is carbon build-up in the intake; in addition, 2017-2020 units had recalls for software and for the fuel pump, since fixed by the manufacturer.^[4][5][6][7]

See the 5 of the Skyactiv-G faults

Side-by-side comparison

Comparison of BMW B38 / B37 and Skyactiv-G
Item	BMW B38 / B37	Skyactiv-G
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,499 cm³	—
Timing	Chain	Chain
Power	75–231 hp	75–187 hp
Production	since 2014^[8][9][10]	since 2011^[4][11]
Reliability
Risk index (what is it?)	20Low risk	25Moderate risk
Documented faults	3	5
Of high or critical severity	1	0
Worst severity	Critical severity	Medium 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	Medium severity: Intake shut-off valve software issue and engine stalling Medium severity: Micro-cracks in the fuel pump impeller Medium severity: ECU programming and loss of power (CX-5 II and Mazda3 IV)
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]	1.5 Skyactiv-G (P5-VPS)^[5][14] 2.0 Skyactiv-G (PE-VPS)^[6][7][15] 2.5 Skyactiv-G (PY-VPS)^[6]
With cautionVersions to be cautious about	B38 1.2 (B38A12, MINI One)^[9] B38 1.5 136 hp up to April 2015 (B38A15)^[1] B38K15T0 231 hp (BMW i8)^[16]	None
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

Skyactiv-G

See the 9 models with the Skyactiv-G

Other comparisons

With the BMW B38 / B37

With the Skyactiv-G

Compare other engines

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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
SkyactivWikipedia (inglés) · Other source · consulted 27 September 2026
Mazda 3 (BM/BN, 2013-2019) – Erfahrungen & ProblemeGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
Mazda 6 (GJ, III) – Erfahrungen & ProblemeGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
Mazda CX-5 II (KF) – Erfahrungen & ProblemeGebrauchtwagenberater · Motoring press · 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 Mazda enginesWikipedia (inglés) · 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
Mazda 2 (DJ) – Erfahrungen & ProblemeGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
Mazda 3 IV (BP) – Erfahrungen & ProblemeGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
BMW i8 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026