Wear at the inboard end of the boost regulator bore in VW/Audi 01M, 01N and 01P units can reduce the ability of EPC/TV pressure to stroke this valve open. Full boost exiting this valve combines forces with the main regulator spring, increasing line pressure. Sonnax oversized boost regulator valve kit 119940-05K allows the valve bores to be refurbished.
Contact a Sonnax Parts Distributor.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.