BMW B48 / B38 vs 1.2 12V: which engine is more reliable?

According to our risk index, the BMW B48 / B38 carries less risk than the 1.2 12V: 24/100 (low risk) versus 57/100 (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 1.2 12V has 2 documented serious faults, the main one being «Timing chain stretch and tensioner wear».

Risk index

BMW B48 / B38

Low risk · 1 serious fault

Lower risk

Risk index

1.2 12V

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 27 September 202615 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 1.2 12V reliable?

The 1.2 12V is a simple, low-power, naturally aspirated three-cylinder engine (54-70 hp), with two documented design faults: the timing chain tensioner, which can end up destroying the engine, and -on the Volkswagen Polo IV- a catalytic converter too close to the cylinder head that can burn the exhaust valves. Ignition coil failures are also common, and there are isolated cases of oil consumption and vibration.^{[4][5][6][7][8]}

See the 5 of the 1.2 12V faults

Side-by-side comparison

Comparison of BMW B48 / B38 and 1.2 12V
Item	BMW B48 / B38	1.2 12V
Technical data
Type	Engine	Engine
Fuel	Petrol	Petrol
Displacement	1,998 cm³	1,198 cm³
Timing	Chain	Chain
Power	136–312 hp	54–70 hp
Production	since 2014^[1][9][10]	2001–2014^[4][11][12]
Reliability
Risk index (what is it?)	24Low risk	57High 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	Critical severity: Timing chain stretch and tensioner wear High severity: Cylinder head and valve damage from exhaust gas backflow (Volkswagen Polo IV) Medium severity: Higher-than-normal oil consumption
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	1.2 54/60 hp (AWY, BMD, BBM, 2001-2014)^[4][6] 1.2 64/70 hp (BME, CGPA, 2002-2014)^{[4][6][14][15]}
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 20 models with the BMW B48 / B38

1.2 12V

See the 7 models with the 1.2 12V

Other comparisons

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With the 1.2 12V

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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
VW Polo 4 (9N): Typische Probleme & SchwachstellenGebrauchtwagenberater.de · Motoring press · consulted 27 September 2026 · in German
Fiabilité et pannes de la Volkswagen Polo 4Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes de la Seat Ibiza (2008-2017)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Seat Ibiza III (2002-2008): Bekannte Probleme & KrankheitenGebrauchtwagenberater.de · Motoring press · consulted 27 September 2026 · in German
Fiabilité et pannes de la Seat Ibiza (2002-2008)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
BMW B38Wikipedia (inglés) · Other source · consulted 27 September 2026
BMW B48Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
VW EA111Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
VW Polo IVWikipedia (alemán) · Other source · consulted 27 September 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
Fiabilité et pannes de la Volkswagen Polo 5Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes de la Skoda Fabia 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French