Question

What is cause of code P0401 and P0402 on my 2000 Ford Ranger 4x4 3.0L?

Answer 1

HI there

P0401, egr insufficient flow

P0402 egr excessive flow

For the first code it's usually carbon build up on the port not allowing egr flow.

The second code would usually be the result of the egr valve sticking open

Answer 2

P0401 FORD - Exhaust Gas Recirculation Flow Insufficient Detected
Read more: https://www.autocodes.com/p0401_ford.html

P0402 FORD - Exhaust Gas Recirculation Flow Excessive Detected
Read more: https://www.autocodes.com/p0402_ford.html