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BMW B48 / B38 vs M111: which engine is more reliable?

According to our risk index, the BMW B48 / B38 carries less risk than the M111: 24/100 (low risk) versus 38/100 (moderate 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 M111 has no documented serious faults.

Risk index

BMW B48 / B38

24

Low risk · 1 serious fault

Lower risk

Risk index

M111

38

Moderate risk · 0 serious faults

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

9 sourcesHow 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 M111 reliable?

The M111 is the four-cylinder petrol engine Mercedes-Benz fitted from 1992 to 2006 in the C-Class (W202 and the early years of the W203), the E-Class (W210), the CLK (C208), the SLK (R170) and the Sprinter, in naturally aspirated form and with a mechanical supercharger (Kompressor). A German used-car guide describes it as reliable when well maintained, with limited weak points: the head gasket and an oil leak into the camshaft adjuster wiring.[4][5]

See the 5 of the M111 faults

Side-by-side comparison

Comparison of BMW B48 / B38 and M111
BMW B48 / B38M111
Technical data
TypeEngineEngine
FuelPetrolPetrol
Displacement1,998 cm³—
TimingChainChain
Power136–312 hp122–197 hp
Productionsince 2014[1][6][7]1992–2006[4][8]
Reliability
Risk index (what is it?)24Low risk38Moderate risk
Documented faults45
Of high or critical severity10
Worst severityHigh severityMedium severity
Main faults
  1. Medium severity: Deterioration of hoses and seals in the cooling circuit, with coolant loss
  2. Medium severity: Oil leaks or seepage from seals and covers, near the turbo and the VANOS
  3. High severity: Timing chain on the early units (2014-2018), redesigned in the B48TU
  1. Medium severity: Head gasket failure with coolant loss
  2. Medium severity: Camshaft adjuster oil leak into the wiring
  3. Medium severity: Mechanical supercharger (Kompressor) wear at high mileage
Most expensive documented repairNo reliable dataNo 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][9]
  • B48 2.0 up to 302-312 hp, high performance (MINI John Cooper Works, BMW X1 M35i)[2]
None
With cautionVersions to be cautious aboutNone
  • M111 naturally aspirated 1.8/2.0/2.2/2.3 (E18/E20/E22/E23)[4][5]
  • M111 Kompressor 2.0/2.3 (E20 ML/E23 ML)[4][5]
AvoidVersions to avoidNoneNone

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 17 models with the BMW B48 / B38

M111

Other comparisons

With the BMW B48 / B38

With the M111

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.

  1. BMW B48Wikipedia (inglés) · Other source · consulted 27 September 2026
  2. Motor BMW B48: defectos, mantenimiento y guía de compraRecambios y Accesorios BMW (blog) · Technical documentation · consulted 27 September 2026 · in Spanish
  3. BMW Reliability Has Changed, But the Internet Hasn't Caught UpBMWBLOG · Other source · published January 2026 · consulted 27 September 2026
  4. Mercedes-Benz M111 engineWikipedia · Other source · consulted 27 September 2026
  5. Mercedes M111: Typische Probleme und HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  6. BMW B38Wikipedia (inglés) · Other source · consulted 27 September 2026
  7. BMW B48Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  8. Mercedes-Benz M 111Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  9. 5 BMWs That Prove the B48 Four-Cylinder Engine Is Better Than You ThinkBMWBLOG · Other source · published April 2026 · consulted 27 September 2026