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  • Converter shudder & TCC slip
  • Engine stall at idle
  • Harsh downshifts
  • No lockup
  • Overheated fluid
  • Poor fuel economy
  • RPM surge on coast
  • TCC apply & release concerns
  • TCC codes


Bore wear at the lockup control valve allows pressure loss that causes driveability concerns.


Eliminate bore wear and restore normal operation by reconditioning the bore and installing Sonnax oversized lockup control valve kit.

U341E, U341F

Oversized Lockup Control Valve Kit
Part No. 37740-08K

You need this if... View Instructions

Toyota/Lexus vehicles equipped with U341E and U341F units may have TCC apply and release concerns such as no lockup, slipping lockup or TCC stuck on. Improper lockup can result in harsh downshifts or engine stall at idle as well as associated trouble codes. On vehicles equipped with a lockup control valve train, bore wear allows control pressure to escape the circuit. Reconditioning the bore and installing Sonnax oversized lockup control valve kit 37740-08K renews TCC operation by restoring critical clearances and preventing pressure loss.

  • Hardcoat anodized aluminum valves combat premature wear
  • Annular grooves help center valve in bore to reduce future side-load wear

Not all U341E and U341F units have a lockup clutch control valve train. Verify this valve train is present prior to ordering kit. Units that do not contain this valve train will have an empty bore.

  • Lockup Control Valve
  • Plunger Valve
  • Plunger Sleeve
  • Retainer

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

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  • 37740 08k combo
  • 37740 08k

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

  • 37740 08k test2
  • 37740 08k test1