Mercedes 722.9 transmissions often suffer shift abnormalities caused by excess wear in either or both of the supply pressure regulator valve bores. The supply pressure regulator controls the pressure supplied to solenoids, and functions similarly to solenoid pressure regulators found in Ford units. This wear allows fluid loss which prevents proper regulation of oil pressure supplied to control solenoids, resulting in harsh or soft shifts, solenoid codes, wrong gear starts, TCC apply issues, and clutch failure.

Reconditioning the bore(s) and installing Sonnax oversized supply pressure regulator valve 88740-02 restores hydraulic integrity to this circuit, restoring normal shift operation and feel in all ranges and the hardcoat anodized aluminum valve combats premature wear.