BMW B38 / B37 vs 1.4 and 1.6 16v: which engine is more reliable?

According to our risk index, the BMW B38 / B37 carries less risk than the 1.4 and 1.6 16v: 20/100 (low risk) versus 45/100 (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 1.4 and 1.6 16v has 1 documented serious fault, the main one being «Timing belt breakage or premature failure».

Risk index

BMW B38 / B37

Low risk · 1 serious fault

Lower risk

Risk index

1.4 and 1.6 16v

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 202621 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 1.4 and 1.6 16v reliable?

The K4J (1.4) and K4M (1.6), both naturally aspirated 16-valve units, are simple and generally reliable petrol engines: no source consulted documents oil consumption or faults that destroy the block. Their most-cited weak point is the ignition coils, followed by the crankshaft sensor and, on versions with a variable valve timing unit, its pulley; a neglected belt can cause serious damage, as one case in the Renault Laguna II documents.^[4][5][6][7]

See the 6 of the 1.4 and 1.6 16v faults

Side-by-side comparison

Comparison of BMW B38 / B37 and 1.4 and 1.6 16v
Item	BMW B38 / B37	1.4 and 1.6 16v
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,499 cm³	—
Timing	Chain	Timing belt (dry)
Power	75–231 hp	75–135 hp
Production	since 2014^[8][9][10]	since 1998^[11][12][13]
Reliability
Risk index (what is it?)	20Low risk	45Moderate risk
Documented faults	3	6
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	Medium severity: Ignition coil failure High severity: Timing belt breakage or premature failure Medium severity: Crankshaft position sensor failure
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^[14] B37TÜ1 1.5 diesel 95-116 hp (from late 2017)^[15]	1.6 16V 105-110 hp Dacia, without variable valve timing unit (K4M, 2004-2020)^[7][16]
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)^[17]	1.4 16V 75-100 hp (K4J, 1999-2012)^[18][19] 1.6 16V 110-135 hp with variable valve timing unit (K4M, 1998-2020)^[6][20][21]
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

1.4 and 1.6 16v

See the 13 models with the 1.4 and 1.6 16v

Other comparisons

With the BMW B38 / B37

With the 1.4 and 1.6 16v

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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 de la Renault Mégane 1Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes du Renault Scénic 1Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes de la Renault Laguna 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes du Dacia Duster 1Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
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
Renault K-Type engineWikipedia (inglés) · Other source · consulted 27 September 2026
Moteur K RenaultWikipedia (francés) · Other source · consulted 27 September 2026 · in French
Anexo:Motores de RenaultWikipedia (español) · Other source · consulted 27 September 2026 · in Spanish
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
Fiabilité et pannes du Dacia Logan 1Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
BMW i8 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026
Fiabilité et pannes de la Renault Clio 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes de la Renault Clio 3Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes de la Renault Mégane 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes du Renault Scénic 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French