Engines · BMW
BMW N54 twin-turbo straight-six common problems
The N54 is a 3.0 litre petrol straight-six with two turbochargers and direct injection, BMW's first mass-produced turbo petrol engine. It arrived in the 335i in 2006, was replaced by the single-turbo N55 from 2009 to 2010 in most models, and carried on in the Z4 sDrive35i until 2016. It is fast and very tunable.
Common problems and what to look for on the N54
The known issues most worth checking when you view a car with this engine. None of them means a car is a bad buy, but they're worth knowing about before you buy, and a good history often shows they've been dealt with.
High-pressure fuel pump failure
What to look for: Start the engine and note whether it cranks for longer than normal before firing. On the test drive, accelerate firmly: stuttering, a sudden loss of power or the car going into a reduced-power mode are the signs. Ask whether the high-pressure fuel pump has been replaced and when.
Why it matters: The pump that feeds fuel to the injectors at high pressure failed often on early N54s. In the US, BMW recalled affected cars and extended the pump warranty to 10 years or 120,000 miles. A car with an invoice for a replacement pump is in a good position.
Leaking or misfiring injectors
What to look for: Listen to the idle for any unevenness, and feel for jerking or misfires under load on the test drive. Check for an engine management light. Ask for invoices for replacement injectors.
Why it matters: The N54 uses piezo injectors, which can leak or fail, causing misfires and lost power. BMW revised the design many times and the later versions are better, though failures still happen. Cars with a full set of later injectors fitted have usually put this behind them.
Wastegate rattle
What to look for: On the test drive, lift off the throttle after accelerating and listen for a metallic rattle from the engine bay. Also watch for a loss of boost, or a car that feels down on power. Ask whether the turbos have been replaced.
Why it matters: The wastegates, which control turbo boost, wear at their bushings and arms and start to rattle. In the US, BMW extended the wastegate warranty to 8 years or 82,000 miles on 2007 to 2010 cars. Over time it can stop the turbo making boost, and the full fix is replacement turbos. A car with replacement turbos on file is in a good position.
More known issues, covered in the full guide for each car
- Electric water pump and thermostat
- Oil leaks from the rocker cover, oil filter housing and sump
- Carbon build-up on the inlet valves
Cars with the N54
- BMW 1 Series E81/E82/E87/E88: 135i coupé and convertible, 2007 to 2010
- BMW 1 Series M Coupé E82: 1M Coupé
- BMW 3 Series E90/E91/E92/E93: 335i, 2006 to 2010
- BMW 5 Series E60/E61: 535i, 2007 to 2010
- BMW 7 Series F01/F02: 740i, to 2012
- BMW X6 E71: xDrive35i, earlier cars
- BMW Z4 E89: sDrive35i and sDrive35is
A pre-purchase inspection guide for your car
The CrankSight guide is a pre-purchase inspection (PPI) you do yourself, written for the exact model and generation you're viewing. It walks you round the car on your phone, with every check for that version, engine included: what to look for, where to find it, and what anything you find is likely to cost. As you go it builds an assessment of that car, and if you view more than one, it lines them up side by side.
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General points for the engine, last checked October 2026. Every car is different, so treat this as a guide to what to look at, not a verdict on any car. CrankSight is independent and has no connection with any manufacturer.