• Solenoid performance codes
  • 2nd Gear starts
  • Soft shifts & poor line rise
  • Harsh shifts
  • No 4th
  • Clutch failure
  • Band failure
  • Wrong gear starts


Actuator feed limit bore wear results in low pressure at shift and EPC solenoids.


Refurbish the bore and install Sonnax AFT valve kit to prevent AFL leakage while providing greater durability and thermal expansion properties.


AFL Valve Kit
Part No. 72854-01K

You need this if... View Instructions Find a Distributor

In GM 4T80-E units, the OE actuator feed limit (AFL) valve routes regulated line pressure to the pressure control and shift solenoids. AFL pressure feeds the pressure control solenoid, which regulates the outgoing torque signal pressure. AFL pressure is directed to the shift solenoids to oppose spring force and stroke the shift valves. Constant oscillation of this hardened steel valve causes the cast aluminum bore to wear, reducing the AFL oil pressure, which can cause solenoid and ratio codes, clutch/band failure and harsh shifts. Bore wear can also cause the valve to stick in the exhaust position, resulting in 2nd Gear starts and low line pressure. Sonnax AFL valve kit 72854-01K re-establishes the hydraulic integrity of the circuit by eliminating and preventing wear in the AFL circuit.

  • Highly wear-resistant aluminum sleeve provides more durability
  • Hardcoat anodized aluminum valve combats premature wear and provides better leakage control during thermal expansion
  • Valve spools have been lengthened to provide better stability and prevent leakage
  • Annular grooves have been added to center the valve and prevent wear from side loading
  • A regulating spring has been added to fit into the lengthened valve and set the correct limiting pressure
  • Sleeve
  • Valve
  • Regulating Spring
  • Retaining Spring
  • Sleeve Retaining Clip
  • 4T80-E AFL Valve Kit 72854-01K
  • 4T80-E AFL Valve Kit 72854-01K

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.

4T80-E AFL Valve Kit Vacuum Test Locations