BMW B38 / B37 vs Porsche MA1 / 9A1: which engine is more reliable?

According to our risk index, the BMW B38 / B37 carries less risk than the Porsche MA1 / 9A1: 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 Porsche MA1 / 9A1 has 1 documented serious fault, the main one being «Bore scoring in the MA1 of the 997.2 and 987.2: uncommon, but documented».

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

Risk index

Porsche MA1 / 9A1

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 2 November 202620 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 Porsche MA1 / 9A1 reliable?

Yes, it is noticeably more reliable than the M96/M97: it eliminated the intermediate shaft with its IMS bearing and, according to FCP Euro, the connecting rod bolt failures. What is documented is minor: carbon build-up on the intake valves caused by direct injection, coolant pump leaks on the 991.1 and, rarely, bore scoring on the 997.2.^[4][5][6][7]

See the 3 of the Porsche MA1 / 9A1 faults

Side-by-side comparison

Comparison of BMW B38 / B37 and Porsche MA1 / 9A1
Item	BMW B38 / B37	Porsche MA1 / 9A1
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,499 cm³	—
Timing	Chain	Chain
Power	75–231 hp	255–400 hp
Production	since 2014^[8][9][10]	2009–2016^{[4][7][11][12][13][14][15]}
Reliability
Risk index (what is it?)	20Low risk	25Moderate risk
Documented faults	3	3
Of high or critical severity	1	1
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: Bore scoring in the MA1 of the 997.2 and 987.2: uncommon, but documented Medium severity: Carbon build-up on the intake valves caused by direct injection Medium severity: Leaks from the electronically controlled coolant pumps of the 991.1 and the plastic water pump
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^[16] B37TÜ1 1.5 diesel 95-116 hp (from late 2017)^[17]	3.6 Carrera 345 hp (MA1.02, 2009-2012)^[4][6][7] 3.8 Carrera S 385 hp (MA1.01, 2009-2012)^[6][7] 2.9 Boxster/Cayman 255-265 hp (MA1.20, 2009-2012, no direct injection)^[5][11]
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)^[18]	3.4 Boxster S / Cayman S 310-320 hp (MA1.21/.22, 2009-2012, direct injection)^[5][19] 3.4 Carrera 350 hp (MA1.04, 2011-2015)^[6] 3.8 Carrera S 400 hp (MA1.03, 2011-2015)^[6] 2.7 Boxster/Cayman 265-275 hp (MA1.22, 2012-2016)^[19][20] 3.4 Boxster S / Cayman S / GTS 315-340 hp (MA1.23, 2012-2016)^[19][20]
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 17 models with the BMW B38 / B37

Porsche MA1 / 9A1

Other comparisons

With the BMW B38 / B37

With the Porsche MA1 / 9A1

Compare other engines

First engine

Second engine

That is the comparison you are viewing: change one of the two engines.

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
The Definitive Guide To Porsche 997 Engines (M96.05, M97, MA1)FCP Euro · Other source · published 16 January 2024 · consulted 2 November 2026
Porsche 987: The Cayman and Boxster Generation GuideRenn Driver · Other source · published 1 November 2026 · consulted 2 November 2026
Porsche 911: 5 Generationen im Gebrauchtwagen-CheckAUTO BILD · Motoring press · published 22 September 2026 · consulted 2 November 2026 · in German
Porsche 997Wikipedia · Other source · consulted 2 November 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
Porsche Boxster and Cayman (987)Wikipedia · Other source · consulted 2 November 2026
Porsche 991Wikipedia · Other source · consulted 2 November 2026
Porsche Boxster and Cayman (981)Wikipedia · Other source · consulted 2 November 2026
Differences between M96 and M97 enginesFlat Six Innovations · Other source · published 25 November 2025 · consulted 2 November 2026
List of Porsche enginesWikipedia · Other source · consulted 2 November 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
Porsche Cayman and Boxster Common Problems: A Specialist Field GuideForeign Automotive · Other source · consulted 2 November 2026
Porsche 981: The Cayman and Boxster Generation GuideRenn Driver · Other source · consulted 2 November 2026