Is your BMW acting up? Rough idle, poor acceleration, or maybe the check engine light is on? A faulty Mass Air Flow (MAF) sensor could be the culprit. This OCPTY replacement MAF sensor is designed to get your Bimmer running smoothly again. It measures the air entering your engine so the computer can mix the perfect air/fuel ratio. This one is a direct fit for a ton of popular BMW models and years, including the 135i, 335i, 535i, 640i, 740i, M235i, and SUVs like the X1, X3, X4, X5, and X6. It also fits the ActiveHybrid 5 and 7 models. It replaces OEM numbers like 5WK97512, 5WK97512Z, and 13627593624. Installation is pretty straightforward if you're handy – basically, disconnect the electrical plug, undo a couple of 7mm bolts (or Phillips screws), swap the old sensor out, and bolt the new one in. Always disconnect the battery before starting, of course. This is a high-quality aftermarket part that delivers accurate readings to your ECU. If your BMW is on the fitment list, this sensor can save you a ton compared to a dealer part. Get your engine's performance back on track!