Question

1998 GMC K3500 diesel with engine code P1656, how can I fix this?

Answer 1

HI there

This is a bad intake camshaft actuator. More than likely the actuator is the cause of the code. Here is some more info

P1656 GMC - Intake Camshaft Actuator Control Circuit
Read more: https://www.autocodes.com/p1656_gmc.html