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BMW B48 / B38 vs M271: which engine is more reliable?

According to our risk index, the BMW B48 / B38 carries less risk than the M271: 24/100 (low risk) versus 59/100 (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 M271 has 1 documented serious fault, the main one being «Timing chain stretch and wear of the camshaft sprockets».

Risk index

BMW B48 / B38

24

Low risk · 1 serious fault

Lower risk

Risk index

M271

59

High risk · 1 serious fault

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 M271 reliable?

The M271 is the four-cylinder petrol engine Mercedes-Benz fitted from 2002 to 2015, first with a mechanical supercharger (Kompressor) and, from 2009, with a turbo in the EVO revision. It has one well-documented weak point across the range: the timing chain and the camshaft sprockets can wear prematurely, a problem a specialist source describes as persistent even after the EVO redesign.[4][5][6]

See the 4 of the M271 faults

Side-by-side comparison

Comparison of BMW B48 / B38 and M271
BMW B48 / B38M271
Technical data
TypeEngineEngine
FuelPetrolPetrol
Displacement1,998 cm³1,796 cm³
TimingChainChain
Power136–312 hp122–204 hp
Productionsince 2014[1][7][8]2002–2015[5][6]
Reliability
Risk index (what is it?)24Low risk59High risk
Documented faults44
Of high or critical severity11
Worst severityHigh severityCritical 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. Critical severity: Timing chain stretch and wear of the camshaft sprockets
  2. Medium severity: Oil leaking from the camshaft adjuster solenoids into the wiring
  3. Medium severity: Crankcase ventilation hose under the supercharger: it cracks and lets in false air
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
  • M271 Kompressor 1.6/1.8 (KE16/KE18)[4]
  • M271 EVO 1.8 turbo CGI (DE18 LA)[4]
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 20 models with the BMW B48 / B38

M271

See the 7 models with the M271

Other comparisons

With the BMW B48 / B38

With the M271

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 M271: Typische Probleme und HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  5. Mercedes-Benz M271 engineWikipedia · Other source · consulted 27 September 2026
  6. Mercedes-Benz M 271Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  7. BMW B38Wikipedia (inglés) · Other source · consulted 27 September 2026
  8. BMW B48Wikipedia (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