In listed Toyota/Lexus transmissions, the continuous oscillation of the pressure regulator valve wears the valve body bore. If severe wear occurs at the balance line circuit, the pressure regulator valve won't stroke to reduce line pressure and feed the converter/lube circuits. This can result in high line pressure, harsh shifts, reduced converter pressure and loss of lube. Severe wear at the other pressure regulator valve circuits can allow line pressure to exhaust or go to sump, resulting in low line pressure, soft shifts, and burned clutches and bands. The Sonnax oversized valves [89010-03K] and 97855-24K allow the valve body to be refurbished to restore proper clearances. See chart to find which part fits your application. Hardened steel valves allow valve body to be refurbished to restore hydraulic integrity.