Continuous oscillation of the converter regulator valve in the cast-aluminum bore causes bore wear, which allows apply oil to leak to exhaust. Another area of concern is the valve bore end plug. The continuous movement of the regulator valve and spring causes the end plug to wiggle in the bore. This movement wears the plug and bore, resulting in balance regulated apply oil leaking to exhaust, which can prevent the converter clutch from applying and set codes.
Contact a Sonnax Parts Distributor.
A vacuumtest at either port indicated fails to hold 18" of vacuum or higher, or if visual wear is detected.