Diagnostic Trouble Codes
 

I have a 2001 F150 6 cyl. I recently failed my emissions test and getting back codes: P0401-exhaust gas restriction flow insufficient detected, P0171-system too lean (bank 1), P0174-system too lean (bank 2). Can anyone help on how to fix this itmes myself or where to begin.

thank you,
Robert

for code po401 replace the dpfe sensor for the others ck for vacume leeks

P0401
 

I changed the ERG Valve and the PDFE switch and it did not fix it. I finally fixed my 98 4.6L F150 with 112,000 miles by cleaning the ERG ports. The ports I'm speaking of can only be accessed my removing the throttle body elbow off the top of the intake manifold. It's an elbow that connects most of the vacuum lines including the ERG Valve. I got a lot of carbon out of their using a drill bit by HAND and that fixed it.

There is a simple test to tell you if the ports are clear. Remove the vacuum line from the ERG Valve and cap the hose. Start the engine and let it idle. Then apply vacuum (outside source) to the ERG Valve. The engine will stumble or stall if the ports are clear. If the engine continues to idle without change the ports are blocked and need to be cleaned. I cleaned mine in about an hour it's not that big of a deal on the 4.6L

Good Luck :-X0A6

...Welcome Jose, to Ford Truck Enthusiasts!

See you on the boards.:-X22 ….

Ah, the trifecta of FAQs for CELS. Have to be the tree most common ones asked about.

SEARCH for "P0401" for that one, and "P0171 P0174" for that combo.



Steve

Just wanted to say thanks to everyone for the info and now I have an idea at what im looking at. Thanks again!