8 Apr 2024The BMW E90 (including E91, E92, and E93 body styles) is a much-loved 3 Series generation—but with age and mileage, there are a few common faults that show up across 318i, 320i, 325i, 330i, 335i, and M3 models.
Here’s a guide to the most frequently failing E90 parts, what goes wrong, and whether it’s something you can sort yourself—or best left to the pros.
1. Rear Window Regulator Lifter for Electric Windows
Fitting Time: 1–2 hours
The most common issue across E90 and E91 models—especially in the rear doors. These cable-driven window regulators often fail due to snapped cables or broken clips, which stop your window from moving.
Issue:
• Window stuck or jammed
• Grinding or popping noise
• Glass drops into the door
Why it fails:
• Cable tension fatigue over time
• Plastic clips break
Good news: You usually don’t need a new motor, just the regulator itself.
There are a few knacks to replacing the regulator but it can be done DIY if you have a bit of mechanical knowledge.
We'd recommend watching this YouTube video to replace the regulator if it's your first time.
Shop Right Rear Window Regulator
Shop Left Rear Window Regulator
2. Electric Water Pump (6-Cylinder Engines)
Fitting Time: 4–6 hours
This is one of the most well-known issues on 6-cylinder BMWs with N52, N53, N54, or N55 engines. Water pumps fail between 90,000–120,000 km and typically bring up warning lights or fault codes like 2E81 (Speed Deviation faults) and 2E82 (Electric Coolant Pump).
Issue:
• Engine overheating
• Coolant warning light
• Electric pump fault codes
Why it fails:
• Internal wear of electronic motor
• Coolant flow failure
• Age and heat cycling
Pro tip: Always replace the thermostat and one-time aluminium bolts which hold on the waterpump at the same time.
It's also best to fully drain your coolant and replace it with 2-3 litres of high-quality coolant and top it up with water too.
If you're doing it yourself it's a good idea to watch this video for some tips on replacing the waterpump, thermostat and alloy bolts.
Shop N52 Water Pump (Non-Turbo) - BMW 330i, 328i & 325i E90 / E91 / E92 N52 & N53 Engines
Shop N54/N55 Water Pump (Turbo) - BMW 335i E90 / E91 / E92 N54 & N55 Engines
3. Alternator
Fitting Time: 2–3 hours
If your battery keeps going flat or you’re seeing overcharging faults, your alternator might be on its way out. These wear with age like any other part.
Issue:
• Battery light on
• Car not charging properly
• Engine cuts out or struggles to start
Why it fails:
• Internal diode or bearing failure
• Voltage regulator faults
Both new and second hand are both good options depending on your budget as a new one can be a fair bit more expensive. However new Alternators do provide a lot more confidence in the parts reliability especially with a high-quality brand like Valeo
Shop BMW E90 Alternators (4-Cylinder & 6-Cylinder)
5. Starter motor For 6 Cylinder BMW's 325i, 330i, 335i, M3
Fitting Time: 2–4 hours
The starter motor tends to slow down over time—or stop altogether. If your lights are on but there's no cranking, this is a common cause.
Issue:
• Slow to crank
• No noise on startup
• Car won’t start despite full battery
Why it fails:
• Internal motor wear
• Electrical contact failure
The most common starter motor to fail is the 6 cylinder ones in the N52, N53, N54 & N55 engines.
7. Valvetronic VVT Motor
Fitting Time: 2–3 hours
An engine light paired with poor performance could be a failing VVT (Valvetronic) motor. This part adjusts valve timing and lives on top of the engine on the rocker cover.
Issue:
• Engine warning light
• Fault codes for Valvetronic
• Hesitation or rough idle
Why it fails:
• Motor wear
• Signal or gear failure
It should be safe to drive to your mechanic, but it should be replaced pretty soon. Check out this video if you want to see some tips on replacing it.
Shop VVT Motor for 4-Cylinder E90 (N46 Engines)
8. Gas Bonnet and boot struts for all BMW E90s
Fitting Time: 10–15 minutes
Bonnet not staying up? Worn struts are an easy fix and help avoid nasty head knocks or dents.
Issue:
• Bonnet won’t stay open
• Sudden slamming
Why it fails:
• Gas leaks from struts
• Seal fatigue
Anyone can replace them themselves with a small flat head screwdriver.
Shop Bonnet Struts for BMW E90
9. Top Radiator Hose
Fitting Time: 1–1.5 hours
The top radiator hose becomes brittle over time and can spring a leak, potentially overheating your engine if left unchecked.
Issue:
• Coolant leaks
• Hose swelling or cracking
• Overheating
Why it fails:
• Rubber degradation
• Heat cycling
If the hose on your e90 is looking perished and likely to fail it's a good idea to replace it before it catches you out.
Shop Top Radiator Hose (6-Cylinder E90)
10. Engine Ignition Coils
Fitting Time: 1–2 hours
Misfires and rough running? Ignition coils are a common cause. When one goes, the others are likely not far behind.
Issue:
• Engine light
• Misfiring
• Rough idle or poor performance
Why it fails:
• Coil pack wear
• Heat and vibration
Tip: It's always a good idea to replace all coils together to avoid the problem happening again soon after.
Shop Ignition Coils for BMW E90
11. Washer motor bottle pump
Fitting Time: 30–60 minutes
Leaking or not spraying? A failed washer pump is easy to replace and helps keep your windscreen clean and safe.
Issue:
• No washer spray
• Fluid leaking at base
• No noise from pump
Why it fails:
• Motor burnout
• Cracked housing
12. Cup Holders
Fitting Time: 30–45 minutes
Stuck or jammed? E90 cup holders often break after 10+ years. Driver’s side usually goes first.
Issue:
• Won’t open
• Stuck in or out
Why it fails:
• Internal spring or latch breakage
Unfortunately we don't currently stock any new cups holders, but we can try find you a good second hand part - just send us a message with your rego number.
13. Oil Level Sensor
Fitting Time: 1.5–2 hours
Erratic oil readings after a service? Faulty oil sensors are a common issue, especially in 4-cylinder and diesel models.
Issue:
• Inaccurate level warnings
• Warning after oil change
Why it fails:
• Sensor failure
• Electrical fault
Shop BMW E90 Oil Level Sensor (4-Cylinder Petrol)
Shop BMW E90 Oil Level Sensor (Diesel)
14. Oil Filter
Fitting Time: 30 minutes
Essential for every oil change. A good quality oil filter helps keep your engine clean and healthy.
Shop Oil Filter for N46 (4-Cylinder E90)
15. Rocker Cover Gasket
Fitting Time: 2–3 hours
Smell burning oil? A leaking rocker cover gasket may be dripping onto your exhaust, which is a serious hazard.
Issue:
• Oil smell in cabin
• Oil on engine block
• Oil leak at top of engine
Why it fails:
• Gasket hardens over time
• Heat cycling
Shop Rocker Cover Gasket for 335i
Shop Rocker Cover Gasket for N46 (4-Cylinder)
We Ship BMW E90 Parts NZ-Wide
From alternators to ignition coils, water pumps to cup holders—we stock both new and used parts for BMW E90s. (This article was designed with BMW 3 Series in mind including the models 318i, 320i, 325i, 330i, 335i, M3 and body shapes E90 LCL E91, E92, E93, Sedan, Coupe and Convertible.)
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