• Delayed engagement
  • Low line rise
  • Low line pressure in Reverse
  • High line pressure in Reverse
  • Erratic line pressure
  • Soft upshifts
  • Repeated clutch failure


Severe wear of the boost sleeve allows TV and boost oil leakage.


The replacement boost valve and sleeve assembly restores hydraulic integrity and prevents cross leaks.


This kit replaces OE valves with .566" and .523" dia. spools. Measure the OE valve and compare dimensions to ensure correct part is ordered.

Part Number Large Spool Small Spool
97855-23K .566 dia. .523 dia.
97855-30K .546 dia. .480 dia.

A340, A340E, A340F, A340H

Boost Valve Kit
Part No. 97855-23K

View Instructions Find a Distributor

The steel OE valve in Toyota/Lexus A340, A340E/F/H type 1 transmissions moves within the cast aluminum sleeve, wearing the sleeve. After this wear becomes severe, the valve no longer operates properly, causing soft upshifts and delayed engagement. Sonnax boost valve kit 97855-23K will restore proper operation.

  • Sleeve made from high-quality aluminum for better wear resistance
  • Hardcoat anodized aluminum valve combats premature wear
  • Valve
  • Sleeve
  • Shims (3)

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/Lexus A340, A340E/F/H Valve Body Layout

Toyota/Lexus A340, A340E/F/H Valve Body Layout
  • A340, A340E, A340F, A340H Boost Valve Kit 97855-23K