320i / 325i 2.5 (N52)

2005–2011 · petrol · 2497cc · 218hp

Engine codes: N52

Reliable

Reliability, common problems and owner reviews for the Bmw 3 Series E90 320i / 325i 2.5 (N52). Check this before you buy used.

The naturally-aspirated straight-six — one of BMW's most dependable modern engines, smooth and long-lived. The known weak points are wear items rather than design killers: electric water pump, plastic thermostat housing and a couple of oil-leak gaskets.

Known Issues

Electric water pump failurerecurring

Electric water pump fails ~130,000–190,000 km, risking overheating.

Fix / Workaround: Replace proactively (pump + thermostat).

Repair cost: €300–€700

Typically appears after: 130,000 km

Thermostat housing / oil leaksrecurring

Plastic thermostat housing cracks; valve-cover and oil-filter-housing gaskets leak.

Fix / Workaround: Replace housing/gaskets.

Repair cost: €150–€600

Typically appears after: 110,000 km

Electric water pump and thermostat failurerecurring

The N52's electric water pump is a known service item — it fails without much warning between roughly 120,000 and 180,000 km, usually together with the electronically-controlled thermostat. Failure means overheating within minutes, and the magnesium-aluminium block does not forgive overheating.

Fix / Workaround: Replace pump + thermostat proactively around 150,000 km or at the first slow-warm-up / overheat warning. Not a cheap part, but far cheaper than a cooked engine.

Repair cost: €450–€900

Typically appears after: 120,000 km

Valvetronic eccentric shaft sensor and oil leaksrecurring

Two classic N52 age items: the Valvetronic eccentric shaft sensor fails (rough running, limp mode), and the valve cover + oil filter housing gaskets harden and leak oil — sometimes onto the belt and alternator below. Lifter tick on cold start at high mileage is also common and mostly benign.

Fix / Workaround: Budget for valve cover and oil filter housing gaskets on any 150k+ example; eccentric shaft sensor is a valve-cover-off job — do them together.

Repair cost: €300–€800

Typically appears after: 140,000 km

Mileage Thresholds

After 250,000 km: Long-lived with cooling/gasket upkeep.

After 150,000 km: Do the electric water pump + thermostat proactively here if there's no record of them being changed — the single most important N52 preventive job.

Fault Codes to Scan

P0128Coolant temperature below thermostat regulating temperature — failing electronic thermostat.recurring

P0011Intake camshaft timing over-advanced — VANOS solenoid contamination; often fixed by cleaning/swapping solenoids.minor

P0301Cylinder misfire — coils and plugs age; on high-mileage cars also check the Valvetronic system.minor

Pre-Purchase Checklist

☐Check cooling system / water pump history
☐Inspect for oil leaks
☐The smart petrol choice

Frequently asked questions

Is the Bmw 3 Series E90 320i / 325i 2.5 (N52) reliable?

Reliable — The naturally-aspirated straight-six — one of BMW's most dependable modern engines, smooth and long-lived. The known weak points are wear items rather than design killers: electric water pump, plastic thermostat housing and a couple of oil-leak gaskets.

What are the common problems and reviews for the Bmw 3 Series E90 320i / 325i 2.5 (N52)?

The most commonly reported problems: Electric water pump failure, Thermostat housing / oil leaks, Electric water pump and thermostat failure, Valvetronic eccentric shaft sensor and oil leaks.

Is a used Bmw 3 Series E90 320i / 325i 2.5 (N52) worth buying?

Minor issues only, easy to maintain, no design flaws. A safe used buy.