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

According to our risk index, the BMW B38 / B37 carries less risk than the 1.0 EcoBoost: 20/100 (low risk) versus 71/100 (high risk). The 1.0 EcoBoost has 3 documented serious faults, the main one being «Degradation of the timing belt running in oil»; the BMW B38 / B37 has 1 documented serious fault, the main one being «B38 crankshaft thrust bearing failure (units before April 2015)».

Risk index

1.0 EcoBoost

High risk · 3 serious faults

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

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

Reviewed on 30 October 202620 sources How we work

Is the 1.0 EcoBoost reliable?

It is a turbocharged direct-injection three-cylinder that has won Engine of the Year several times, but it has two very well-documented weak points: two belts running in oil (timing and oil pump) that can disintegrate and seize the engine, and cases of coolant leaks and overheating in early units. It is best bought with a service history and the belts checked or replaced on time.^[1][2][3][4]

See the 4 of the 1.0 EcoBoost faults

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.^[5][6][7]

See the 3 of the BMW B38 / B37 faults

Side-by-side comparison

Comparison of 1.0 EcoBoost and BMW B38 / B37
Item	1.0 EcoBoost	BMW B38 / B37
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	999 cm³	1,499 cm³
Timing	Wet belt (belt-in-oil)	Chain
Power	100–155 hp	75–231 hp
Production	since 2012^{[1][8][9][10]}	since 2014^[11][12][13]
Reliability
Risk index (what is it?)	71High risk	20Low risk
Documented faults	4	3
Of high or critical severity	3	1
Worst severity	Critical severity	Critical severity
Main faults	Critical severity: Degradation of the timing belt running in oil Critical severity: Oil pump belt and tensioner failure Critical severity: Coolant leaks and overheating from the turbo hose	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
Most expensive documented repair	up to €1,200Degradation of the timing belt running in oilPublished figure^[2]	No reliable data
Which versions to buy
BuyRecommended versions	None	B38 1.5 136-140 hp from April 2015 (B38A15 / B38B15)^[5] B37 1.5 diesel 95-116 hp (B37C15K0 / B37C15U0), up to 2017^[14] B37TÜ1 1.5 diesel 95-116 hp (from late 2017)^[15]
With cautionVersions to be cautious about	1.0 EcoBoost 100/125 (Fox, 2012-2017)^[2][3][16] 1.0 EcoBoost 100/125/140 with cylinder deactivation (from ~2017)^[17][18] 1.0 EcoBoost Hybrid 48V mild hybrid (125/155 hp, from 2019)^[1][19]	B38 1.2 (B38A12, MINI One)^[12] B38 1.5 136 hp up to April 2015 (B38A15)^[5] B38K15T0 231 hp (BMW i8)^[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

1.0 EcoBoost

See the 11 models with the 1.0 EcoBoost

BMW B38 / B37

See the 14 models with the BMW B38 / B37

Other comparisons

With the 1.0 EcoBoost

With the BMW B38 / B37

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.

Ford EcoBoost engineWikipedia · Other source · consulted 26 September 2026
Alerta Ford: la correa de distribución del 1.0 EcoBoost puede romper el motor y la NHTSA ya investigaMotor16 · Motoring press · consulted 26 September 2026 · in Spanish
Los Ford 1.0 EcoBoost tricilíndricos están dando problemas de correas bañadas que recuerdan al caso PureTechMotor.es · Motoring press · consulted 26 September 2026 · in Spanish
Gripa el motor por problema en el manguito se queda sin refrigeranteOpinautos · Owners' forum · consulted 26 September 2026 · in Spanish
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
Prueba: Ford Fiesta 1.0 EcoBoost 100 CV (2013)km77 · Motoring press · consulted 26 September 2026 · in Spanish
Ford Mondeo Berlina Trend 1.0 EcoBoost 92 kW (125 CV) (2015-2018): precio y ficha técnicakm77 · Technical documentation · consulted 26 September 2026 · in Spanish
Ford B-MAX Trend 1.0 EcoBoost 100 CV (2012-2018): precio y ficha técnicakm77 · Technical documentation · consulted 26 September 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
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
Ford EcoBoost engines: reliability, problems and should you buy one?Carbuyer · Motoring press · consulted 26 September 2026
Ford's Self-Clogging 1.0-Liter EcoBoost Engine Is Finally Getting RecalledThe Drive · Motoring press · consulted 26 September 2026
The Largest Ford EcoBoost Recalls In 15 Years Of ProductionCarBuzz · Motoring press · consulted 26 September 2026
Stellantis no es el único afectado por la correa de distribución bañada en aceiteAutofácil · Motoring press · consulted 26 September 2026 · in Spanish
BMW i8 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026