• Line pressure instability
  • Burnt clutches & bands
  • Low EPC pressure
  • Low line pressure


Fluid leaking past OE pressure regulator end plug.


Sonnax drop-in O-ringed plug kit eliminates leakage at the bore plug.


O-Ringed End Plug Kit
Part No. 73840-06

Fits pressure regulator valve bore.

View Instructions Find a Distributor

Ford CD4E and Mazda LA4A-EL transmissions often develop a leaky end plug at the pressure regulator bore causing line pressure instability, low EPC pressure and ultimately resulting in burnt clutches and bands. Replacing the OE end plug with Sonnax O-ringed end plug kit 73840-06 provides a solid seal to halt TV/EPC pressure loss from this circuit. Drop-in Zip Valve parts install quickly and easily.

Learn More About Zip Valve™ Drop-In Repairs

Can be used with OE pressure regulator valve or with Sonnax oversized pressure regulator valve 73840-RK.

  • End Plug
  • O-Ring
  • CD4E, LA4A-EL O-Ringed End Plug Kit 73840-06
  • CD4E, LA4A-EL O-Ringed End Plug Kit 73840-06