Sonnax U140E Transmission Boost Valve Kit 57917E-01K Toyota vehicles with U140E/F, U240E and U241E transmissions may exhibit insufficient line rise in the drive ranges and excessively high pressures in reverse. This may be caused by continuous oscillation of the steel boost valve within the cast-aluminum sleeve, creating excessive wear and a path for EPC and reverse pressures to leak. This Sonnax boost valve kit 57917E-01K has upgraded materials and minimal clearances to prevent wear and restore proper hydraulic control. Boost sleeve manufactured from highly wear-resistant billet aluminum to prevent the excessive wear exhibited by the cast OE sleeve Restores proper line rise Contents Valve Sleeve Plug