I have '97 ford ranger 3.0 4x2 5 spd. 6months ago the check engine light came on and the code was in the 400's saying to check the EGR system. I changed the EGR valve and cleaned all the hoses, pipes and even took the air intake assembly off and had it cleaned. The light went off and the truck ran with no problems. Until the other day when the light came back on and the code was 401; EGR air flow insuficient. The valve works, the hoses are clean. what else could it be? the TPS or EGRS what?

 

I have a 97' 3.0 and it had the same code. My problem was the DPFE sensor, a rectangular aluminum box, Located to the rear of the EGR. The original DEFE will rust on the inside. The replacement is made of plastic.

 

Thanks a million! I kind of suspected a sensor, but hard to say which one.