8HP45 Transmission Solenoid Kit for BMW X3 and X5

Solenoid set for the ZF 8HP45 eight-speed mechatronic unit. On these boxes the solenoids sit on the valve body inside the mechatronic assembly and do all the pressure control - line pressure, clutch apply, and torque converter lockup. When one starts sticking or drifting out of calibration you get the classic 8HP complaints: a hard bang on the 1-2, a long flare between gears, converter shudder at light throttle around 40-50 mph, or the box dropping into limp and holding one gear. Pressure control solenoid codes almost always point here rather than at the clutches.

These are remanufactured units, not new. They are pulled, cleaned, inspected, and flow tested before they ship, so expect normal cosmetic wear on the bodies. That is the trade for the price - a new mechatronic unit from the dealer is several thousand dollars, and in most cases the mechanical side of the transmission is fine and only the solenoids have worn.

Listed OE references are 8HP45, 8HP70, and 8HP90. Vehicle fitment per the manufacturer covers BMW X1 2.0L 2016, X3 2.0L 2013-2016, X3 3.0L 2011-2016, X5 2.0L 2016, X5 3.0L 2013-2016, X5 4.4L 2013-2016, X6 3.0L 2012-2016, X6 4.4L 2012-2016, Z4 2.0L 2012-2016, Dodge Charger 6.4L 2012-2016, and Dodge Durango 5.7L 2012-2016. Check your existing solenoid connector layout against the photos before ordering, since ZF ran several internal variants across that span.

Plan on dropping the pan and pulling the mechatronic unit to do the job. The pan on an 8HP is the filter, so it is replaced as an assembly, and the transmission gets refilled and level-set at temperature through the fill plug afterward. Most shops also clear adaptations and let the box relearn after the swap. This is not a driveway job on a lift-less car - budget for professional installation if you are not set up for it.