High-mileage vehicles with a THM 200/200C often experience poor line pressure control due to a worn pressure regulator bore. This can result in high cooler pressure as well as converter and/or friction element failure. The hardened steel valve continuously oscillates within the cast-iron pump bore, resulting in wear. Orificed line/balance pressure is then allowed to leak past the valve and exhaust to the sump. This prevents the pressure regulator valve from staying in its normal regulating position. Sonnax offers a pressure regulator valve kit 65912-01K that eliminates these problems.