AW55-50SN Transmission Valve Body with Solenoids

This is a complete AW55-50SN valve body with the solenoid pack already installed, so you are swapping one assembly instead of pulling eight solenoids off a core and hoping they all read in spec. The Aisin-Warner AW55-50SN is the five-speed front-wheel-drive transaxle sold under several names, and this unit carries the OEM references AW55-50SN, AW55-51SN and RE5F22A. Listed fitment covers Nissan Maxima and Altima, Saab, Saturn and Volvo applications from 2004 to 2009.

The reason this unit gets replaced is almost always electrical rather than mechanical. The shift and pressure-control solenoids in this family degrade with heat and miles, and the symptoms show up as a harsh or flared 1-2 shift, a slip on the 3-4, a unit that drops to limp and holds one gear, or torque converter clutch shudder at light throttle. Scan tool codes usually point at individual solenoid circuits, but by the time one is failing the rest are the same age and the same mileage, which is why techs replace the whole valve body instead of chasing them one at a time.

On the bench the job is straightforward: drop the pan, pull the filter, unplug the internal harness connector, back out the valve body bolts in order and lower the old unit out. Keep the checkballs and the separator plate orientation straight on the way apart, transfer the internal harness if your application reuses it, and torque the new body down evenly working from the center out so the separator plate is not distorted. Refill with the correct fluid for the application, check level at operating temperature, and let the TCM relearn its adapts over the first several drive cycles before judging shift quality.

This is a new aftermarket replacement assembly, not a remanufactured core, and it ships from a US warehouse. If you are already inside the unit for a filter and fluid service and the shift complaint is electrical, replacing the valve body at the same time saves you doing the pan twice.