BMW B48 / B38 vs M50 and M52: which engine is more reliable?

According to our risk index, the BMW B48 / B38 carries less risk than the M50 and M52: 24/100 (low risk) versus 52/100 (high risk). The BMW B48 / B38 has 1 documented serious fault, the main one being «Timing chain on the early units (2014-2018), redesigned in the B48TU»; the M50 and M52 has 2 documented serious faults, the main one being «Cooling system failure (expansion tank, thermostat, pump and radiator)».

Risk index

BMW B48 / B38

Low risk · 1 serious fault

Lower risk

Risk index

M50 and M52

High 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 2 November 202616 sources How we work

Is the BMW B48 / B38 reliable?

The BMW B48 (2.0 turbo, from 2014) and its three-cylinder sibling, the B38 (1.5), have a reputation as reliable engines within BMW's modern range: there is no serious, widespread fault on record, unlike the timing chain on the N47 diesel or the EGR fire risk on the B47. Keep an eye on the cooling circuit, the oil seals near the turbo and the VANOS, and the carbon build-up typical of direct injection; BMW revised the timing chain in 2018 (B48TU update).^[1][2][3]

See the 4 of the BMW B48 / B38 faults

Is the M50 and M52 reliable?

The M52 and its predecessor the M50 are six-cylinder petrol engines that the sources describe as durable: Enginescope considers 300,000 km routine with the cooling circuit looked after. Watch the plastic cooling parts, VANOS, crankcase ventilation and oil leaks and, in the aluminium-block M52s built from 1995 to March 1998, cylinder wear caused by sulphur (Nikasil).^[4][5][6]

See the 5 of the M50 and M52 faults

Side-by-side comparison

Comparison of BMW B48 / B38 and M50 and M52
Item	BMW B48 / B38	M50 and M52
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,998 cm³	—
Timing	Chain	Chain
Power	136–312 hp	150–193 hp
Production	since 2014^[1][7][8]	1990–2001^{[9][10][11][12]}
Reliability
Risk index (what is it?)	24Low risk	52High risk
Documented faults	4	5
Of high or critical severity	1	2
Worst severity	High severity	Critical severity
Main faults	Medium severity: Deterioration of hoses and seals in the cooling circuit, with coolant loss Medium severity: Oil leaks or seepage from seals and covers, near the turbo and the VANOS High severity: Timing chain on the early units (2014-2018), redesigned in the B48TU	High severity: Cooling system failure (expansion tank, thermostat, pump and radiator) Critical severity: Premature cylinder wear (Nikasil coating) Medium severity: Worn VANOS seals
Most expensive documented repair	No reliable data	No reliable data
Which versions to buy
BuyRecommended versions	B38 1.5 136 hp (MINI Cooper, 118i)^[2] B48 2.0 178-197 hp (120i, 220i, 320i, 520i, X1/X2/X3 20i, MINI Cooper S)^[2] B48 2.0 252-258 hp (330i, 530i, X3/X4 xDrive30i)^[2][13] B48 2.0 up to 302-312 hp, high performance (MINI John Cooper Works, BMW X1 M35i)^[2]	None
With cautionVersions to be cautious about	None	M50B20, 2.0 litre (150 hp; 1990-1995)^[14][15] M50B25, 2.5 litre (192 hp; 1990-1995)^[14][15] M52B20, 2.0 litre (150 hp; 1994-1999)^[10][14] M52B25, 2.5 litre (170 hp; 1995-1999)^[10][14] M52B28, 2.8 litre (193 hp; 1995-1999)^[10][14][16] M52TUB20, 2.0 litre (150 hp; 1998-2001)^[9][14] M52TUB25, 2.5 litre (170 hp; 1998-2000)^[9][14] M52TUB28, 2.8 litre (193 hp; 1998-2001)^[6][9][14]
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 B48 / B38

See the 21 models with the BMW B48 / B38

M50 and M52

Other comparisons

With the BMW B48 / B38

With the M50 and M52

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Sources

Every fact on this page links to its source. If you find an error, let us know.

BMW B48Wikipedia (inglés) · Other source · consulted 27 September 2026
Motor BMW B48: defectos, mantenimiento y guía de compraRecambios y Accesorios BMW (blog) · Technical documentation · consulted 27 September 2026 · in Spanish
BMW Reliability Has Changed, But the Internet Hasn't Caught UpBMWBLOG · Other source · published January 2026 · consulted 27 September 2026
BMW 3 Series E36 320i (M52B20): reliabilityEnginescope · Other source · consulted 2 November 2026
BMW M52 reliabilityAutoscore · Other source · consulted 2 November 2026
BMW M52 Engine: Performance, Reliability, and TuningBMWBlog · Motoring press · consulted 2 November 2026
BMW B38Wikipedia (inglés) · Other source · consulted 27 September 2026
BMW B48Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
BMW M52Wikipedia (inglés) · Other source · consulted 2 November 2026
BMW M52Wikipedia (alemán) · Other source · consulted 2 November 2026 · in German
BMW M50Wikipedia (inglés) · Other source · consulted 2 November 2026
BMW M50Wikipedia (alemán) · Other source · consulted 2 November 2026 · in German
5 BMWs That Prove the B48 Four-Cylinder Engine Is Better Than You ThinkBMWBLOG · Other source · published April 2026 · consulted 27 September 2026
BMW M50 / M52: problemas conocidosEnginescope · Other source · consulted 2 November 2026
Der BMW M50 Motor: Technische Daten, Probleme, Haltbarkeit & FahrzeuglisteCarWiki.de · Other source · consulted 2 November 2026 · in German
BMW Z3 Reliability Guide: Everything You Need to Know Before BuyingEuro Premium Parts · Technical documentation · consulted 2 November 2026