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BMW B38 / B37 vs BMW N20: which engine is more reliable?

According to our risk index, the BMW B38 / B37 carries less risk than the BMW N20: 20/100 (low risk) versus 63/100 (high risk). The BMW B38 / B37 has 1 documented serious fault, the main one being «B38 crankshaft thrust bearing failure (units before April 2015)»; the BMW N20 has 2 documented serious faults, the main one being «Timing chain guide and tensioner wear (2011-2015)».

Risk index

BMW B38 / B37

20

Low risk · 1 serious fault

Lower risk

Risk index

BMW N20

63

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

12 sourcesHow 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 BMW N20 reliable?

The BMW N20 (2011-2017) was the first turbocharged four-cylinder with which BMW replaced its naturally aspirated six-cylinders in models such as the 320i, 328i and X3, and it is generally mechanically sound. Its best-documented weak point is the timing chain guides and tensioner on units built before 2015; oil leaks, the electric water pump and, to a lesser extent, the turbo and the high-pressure fuel pump are also known issues.[4][5]

See the 5 of the BMW N20 faults

Side-by-side comparison

Comparison of BMW B38 / B37 and BMW N20
BMW B38 / B37BMW N20
Technical data
TypeEngineEngine
FuelPetrolPetrol
Displacement1,499 cm³1,997 cm³
TimingChainChain
Power75–231 hp156–245 hp
Productionsince 2014[6][7][8]2011–2017[4][9]
Reliability
Risk index (what is it?)20Low risk63High risk
Documented faults35
Of high or critical severity12
Worst severityCritical severityCritical severity
Main faults
  1. Critical severity: B38 crankshaft thrust bearing failure (units before April 2015)
  2. Medium severity: Coolant leaks and water pump or thermostat failure on the B38
  3. Low severity: Carbon build-up on the B38's intake valves and injectors
  1. Critical severity: Timing chain guide and tensioner wear (2011-2015)
  2. Critical severity: Electric water pump failure (BMW campaign in the US over fire risk)
  3. Medium severity: Oil leaks from the rocker cover gasket and the filter housing
Most expensive documented repairNo reliable dataNo 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[10]
  • B37TÜ1 1.5 diesel 95-116 hp (from late 2017)[11]
None
With cautionVersions to be cautious about
  • B38 1.2 (B38A12, MINI One)[7]
  • B38 1.5 136 hp up to April 2015 (B38A15)[1]
  • B38K15T0 231 hp (BMW i8)[12]
  • N20B20 156 hp (115 kW, 2013-2016)[5]
  • N20B20B 184 hp (135 kW, 2011-2017)[5]
  • N20B20 218 hp (160 kW, 2012-2015)[5]
  • N20B20A 245 hp (180 kW, 2011-2017)[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 B38 / B37

See the 16 models with the BMW B38 / B37

BMW N20

See the 8 models with the BMW N20

Other comparisons

With the BMW B38 / B37

With the BMW N20

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 Dreizylinder: Dauertest-Probleme des B38 behoben?BimmerToday · Motoring press · published 5 October 2017 · consulted 4 October 2026 · in German
  2. 2024: BMW recall due to EGR coolers extended againcar-recalls.eu · Motoring press · published 28 March 2024 · consulted 4 October 2026
  3. BMW diésel Europa: llamada a revisión por el EGR y riesgo de incendioDiariomotor · Motoring press · consulted 4 October 2026 · in Spanish
  4. BMW N20Wikipedia (inglés) · Other source · consulted 27 September 2026
  5. BMW N20 Engine: Pros, Cons, Reliability, Tuning, and Maintenance GuideBMW BLOG · Motoring press · published 8 June 2025 · consulted 27 September 2026
  6. BMW B38 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026
  7. BMW B38 (Wikipedia, alemán)Wikipedia · Other source · consulted 4 October 2026 · in German
  8. BMW B37 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026
  9. BMW N20Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  10. 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
  11. BMW Baukasten-Diesel: Mehr Infos zur TÜ1 für B47 und B37BimmerToday · Motoring press · published 20 November 2017 · consulted 4 October 2026 · in German
  12. BMW i8 (Wikipedia)Wikipedia · Other source · consulted 4 October 2026