November 08, 2023
Vehicles with listed Toyota transmissions may exhibit insufficient line rise in drive ranges, soft shifts and/or burnt C1 clutches. These problems may be caused by continuous oscillation of the C1 apply boost valve within the boost sleeve, creating excessive wear and a path for line pressure fluid to leak to exhaust. Sonnax C1 apply boost valve kit 168740-01K has upgraded materials and minimal clearances to prevent wear and restore proper hydraulic control.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.