Description
A common problem found on Diesel engines that use VNT (variable nozzle turbine) vanes to regulate air flow through the turbine, a sticky VNT turbo actuator can cause limp mode by not moving the vanes as the computer expects.
At low engine speed, the vanes close to restrict the exhaust air flow through the turbine, increasing turbine power & boost pressure; at higher engine speeds, the vanes open to maximize exhaust gas flow.