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  • Erratic TCC apply pressure
  • Excess TCC slip
  • Harsh TCC apply & release
  • Low cooler & lube pressure
  • TCC codes


Bore wear at the lubrication pressure regulator valve allows critical fluid to escape the circuit, resulting in erratic TCC/lube/cooler pressures.


Recover hydraulic control and revive TCC/lube/cooler pressures by reconditioning the bore and installing Sonnax oversized lubrication pressure regulator valve kit.


Oversized Lubrication Pressure Regulator Valve Kit
Part No. 88740-09K

You need this if... View Instructions

Vehicles with Mercedes 722.9 transmissions commonly have TCC problems such as harsh apply and release or excess slip, often accompanied by TCC codes. These issues can be caused by bore wear at the lubrication pressure regulator valve, which allows vital fluid to escape the circuit. In addition, cooler and lube pressures can be negatively affected. Reconditioning the bore and installing Sonnax oversized lubrication pressure regulator valve kit 88740-09K restores critical clearances for renewed TCC, cooler and lube operation.

  • Hardcoat anodized aluminum valve combats premature wear
  • Springs calibrated and matched to valve to revive OE pressures
  • Valve
  • Spring Blue, Selective
  • Spring Red, Selective

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

Mercedes 722.9 Valve Body Layout

Merc7229 vbl

September 30, 2005

Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits

Gregg Nader

Topics: Diagnostics And Theory Transmission

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  • 88740 09k combo
  • 88740 09k

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

  • 88740 09k test