sonnax-black Facebook-color LinkedIn-color maillink printlink r_and_r_only SERVOFIX-logo-web Twitter-color VBFIX-logo-web video-logo-web warranty_only Youtube-color


  • Burnt clutches
  • Delayed engagement
  • Erratic line pressure
  • Low line rise
  • Low Reverse boost
  • No Reverse
  • Poor shift quality
  • Reverse slip


OE boost sleeve deterioration allows pressure loss that leads to driveability concerns.


Recover hydraulic control and renew shift performance by installing Sonnax boost valve kit.

U341E, U341F

Boost Valve Kit
Part No. 37740-01K

You need this if... View Instructions

Toyota/Lexus vehicles equipped with U341E and U341F transmissions may exhibit insufficient line rise, resulting in delayed engagement, slipping in Reverse, poor shift quality and burnt clutches. These troubles can often be traced to wear in the OE boost sleeve, which allows pressure escape that causes driveability concerns. Installing Sonnax boost valve kit 37740-01K eliminates pressure loss and revives line rise and shift quality in all ranges.

  • Sleeve manufactured from highly wear-resistant aluminum
  • Hardcoat anodized aluminum valve combats premature wear
  • Annular groove helps center valve in sleeve to reduce side-load wear
  • Shims allow adjustable OE base line pressure to be matched
  • Boost Valve
  • Boost Sleeve
  • Shims (2)

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

Toyota U341E/F Valve Body Layout

Toyotau341ef vbl thumb
  • 37740 01k combo
  • 37740 01k
  • 37740 01k measure

You need this if...

OE boost sleeve wear is visually detected.