GM trucks equipped with Allison® 1000/2000/2400 transmissions often go into failsafe mode with codes P1711 or P0872 set in computer memory. This can be caused by bore wear at the E-shift valve, which allows the valve to hang up in the bore. Reconditioning the bore and installing Sonnax oversized E-shift valve kit 37000-15K restores normal operation by renewing critical clearances to allow smooth valve movement and the hardcoat anodized aluminum valve combats premature wear.