HELLO,

PLEASE I NEED TO KNOW IF A LEAK IN THE EXHAUST SYSTEM (FLEX PIPE) CAN AFFECT THIS CODE P0401 FOR LOW EGR FLOW.

IF ANYONE CAN TELL ME ANYTHING FOR THIS CODE. THE TRUCK HAS A FAN CLUTCH BUT THE COMPUTER KEEPS GIVING ME THIS CODE P1491 RADIATOR FAN RELAY OPEN CIRCUIT OR SHORT. TRYED TO CLEAR THE CODE BUT IT COMES RIGHT BACK ON. THANK YOU