A used-car buyer's guide to the N54 BMW 335i, 135i and 535i: what goes wrong by mileage, what owners actually paid to fix it, and a pre-purchase inspection checklist.
Covers: 2007–2010 335i, 2008–2010 135i and 535i, plus 335is, 1M and Z4 35i/35is. Twin-turbo 3.0 inline six.
The N54 is the engine people buy these cars for, and it's also the reason some of them end up cheap. None of its problems are mysteries. They're well documented, parts are easy to find, and any decent independent BMW shop has done each job many times. The trick is knowing which of them the car in front of you has already had done, and which ones are still coming.
What to look for
- Service records that show the high-pressure fuel pump, injectors and water pump, with dates and mileage. A stack of receipts is worth real money on this car.
- Which injector index (revision) is installed if the injectors were replaced. Shops can read it, and the later ones are the ones you want.
- Signs of tuning: a JB4 box, downpipes, a changed charge pipe or a blow-off valve. Tuned is not automatically bad, but you want to know, and plugs and coils wear faster.
- Oil on the exhaust side of the head or a burning smell after a drive (valve cover or oil filter housing gasket).
- A long crank before it fires on a cold start, which can point to the fuel pump.
- Coolant warnings, or fans running hard after you shut it off.
- Rattle from the turbos on deceleration (wastegates).
- Clunk or vague steering under braking, which on E90-chassis cars is often the front thrust arm bushings.
Problems by mileage
Roughly when owners and shops report each problem. Plenty of cars go longer and some fail sooner, so use this to know what to ask about, not as a schedule.
Misfires under load, especially with a tune.
Long crank before it starts, a stumble under boost, reduced-power message, fuel pressure codes.
Misfire on one cylinder, rough cold start, fuel smell, sometimes smoke.
Coolant temp warning, fans running hard after shutdown, drop in power.
Burning oil smell, oil on the exhaust side of the head, sometimes a misfire if oil reaches the plug wells.
Oil seeping down the front of the engine, a wet serpentine belt, burning smell.
A metallic rattle when you let off the gas or at cold start, sometimes boost codes.
Rough idle, cold-start misfire, slowly fading power.
Oil drips under the engine, wet oil pan edge.
Full BMW N54 problem list with what each fix costs →
Repair costs to budget for
Only jobs we have cited owner reports for. If a job isn't here, we don't have enough real prices for it yet.