Reliability Summary

Best engine B48 — 82/100 BUY
Worst engine N20 — 58/100 CAUTION
Average reliability 70/100

Engine Comparison

Engine Reliability Score Verdict Known Issues
B48
2.0L Turbo I4
82/100 BUY Coolant vent line failure +2
N20
2.0L Turbo I4
58/100 CAUTION Timing chain + guide + tensioner — class-action +2

Engines in this model

Known Issues Across All Engines

Issue Engine Severity Onset
Coolant vent line failure B48 moderate 40,000 km – 100,000 km
Oil filter housing gasket — early units (2014-2016) B48 moderate 40,000 km – 100,000 km
Intake valve carbon buildup (DI) B48 minor 60,000 km – 120,000 km
Timing chain + guide + tensioner — class-action N20 critical 60,000 km – 120,000 km
Electric water pump failure N20 high 80,000 km – 140,000 km
Oil filter housing gasket leak N20 moderate 60,000 km – 120,000 km

FAQ

Is the BMW 125i reliable?

The BMW 125i has 2 engine options with reliability scores ranging from 58/100 (CAUTION) to 82/100 (BUY). Average reliability: 70/100.

Which BMW 125i engine is most reliable?

The B48 is the most reliable engine in the BMW 125i, scoring 82/100 (BUY).

What problems does the BMW 125i have?

Across all engine variants, the BMW 125i has 6 known issues. The most common are related to Coolant vent line failure, Oil filter housing gasket — early units (2014-2016), Intake valve carbon buildup (DI).