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

According to our risk index, the BMW B38 / B37 carries less risk than the Mitsubishi PHEV: 20/100 versus 24/100 (both low risk). The BMW B38 / B37 has 1 documented serious fault, the main one being «B38 crankshaft thrust bearing failure (units before April 2015)»; the Mitsubishi PHEV has 2 documented serious faults, the main one being «Corroded air flow sensor: the petrol engine does not start to charge the battery».

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

Risk index

Mitsubishi PHEV

Low 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 202618 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 Mitsubishi PHEV reliable?

Yes, with caveats: the OCU ranks the Outlander PHEV first for reliability among used plug-in hybrids. What is documented are isolated campaigns (spark plugs and software, air flow sensor, fuel hose) and a possible loss of battery capacity, cited by one source and one study without figures. The Eclipse Cross PHEV, which uses the same system, has no documented faults of its own.^{[4][5][6][7][8]}

See the 5 of the Mitsubishi PHEV faults

Side-by-side comparison

Comparison of BMW B38 / B37 and Mitsubishi PHEV
Item	BMW B38 / B37	Mitsubishi PHEV
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,499 cm³	—
Timing	Chain	Chain
Power	75–231 hp	163–224 hp
Production	since 2014^[9][10][11]	since 2013^[12][13][14]
Reliability
Risk index (what is it?)	20Low risk	24Low 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	Medium severity: Loss of traction battery (high-voltage) capacity Medium severity: Spark plugs and petrol engine software on the Outlander PHEV (campaign R3033111) High severity: Corroded air flow sensor: the petrol engine does not start to charge the battery
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^[15] B37TÜ1 1.5 diesel 95-116 hp (from late 2017)^[16]	2.4 Eclipse Cross PHEV (4B12, 13.8 kWh battery, 2021-2024)^[7][8]
With cautionVersions to be cautious about	B38 1.2 (B38A12, MINI One)^[10] B38 1.5 136 hp up to April 2015 (B38A15)^[1] B38K15T0 231 hp (BMW i8)^[17]	2.0 Outlander PHEV (4B11, 12 kWh battery, 2013-2018)^[6][7][18] 2.4 Outlander PHEV (4B12, 13.8 kWh battery, 2018-2021)^[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 14 models with the BMW B38 / B37

Mitsubishi PHEV

Other comparisons

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With the Mitsubishi PHEV

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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
Mitsubishi Outlander PHEV, el híbrido enchufable de segunda mano más fiable según la OCUHíbridos y Eléctricos · Motoring press · published 14 May 2024 · consulted 8 October 2026 · in Spanish
Mitsubishi Outlander (II & III) – Bekannte Probleme und MängelGebrauchtwagenberater (Alemania) · Motoring press · published 2 March 2023 · consulted 8 October 2026 · in German
Baterías de híbrido enchufable: cuándo habrá que sustituirlas (Outlander PHEV)Autofácil · Motoring press · published 7 May 2020 · consulted 8 October 2026 · in Spanish
DVSA – base de llamadas a revisiónDVSA (Reino Unido) · Other source · consulted 8 October 2026
El Mitsubishi Eclipse Cross PHEV sí llegará a Europa, incluida España, en 2021Híbridos y Eléctricos · Motoring press · published 18 October 2020 · consulted 8 October 2026 · in Spanish
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
Mitsubishi Outlander PHEVWikipedia (inglés) · Other source · consulted 8 October 2026
Mitsubishi OutlanderWikipedia (alemán) · Other source · consulted 8 October 2026 · in German
Mitsubishi 4B1 engineWikipedia (inglés) · Other source · consulted 8 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
Mitsubishi Outlander PHEV (2013 – 2014): alerta A12/1947/19 (sensor de caudal de aire)car-recalls.eu (alertas Safety Gate / RAPEX) · Other source · published 13 December 2019 · consulted 8 October 2026