So i have had a check engine light on my for a while now. The codes it it throwing are 411(air injection system),136(farthest back o2 sensor),401, and 402. 401 and 402 seem to counter each other, one is gas reticulation not effective and the other is to much reticulation. This is referring to the EGR system correct? What is causing these codes the o2 sensor or the air injection system, maybe both? If it is the o2 sensor how do i access the final o2 sensor? It is between the cats on the top of the exhaust pipe. If it is the air injection system what would be the issue with that? Seems to me it could be getting bad readings from the o2 sensor making it run to much or not enough? How can i check if my EGR valve is going bad or not?

 

I assume these are Pxxxx codes from your 1996 F150? Please add the details of the truck you are working on in your message body or add it to your signature.

 

You have 3 different problems, potentially a bad O2 sensor, a broken vacuum line or stuck valve in the air injection system, and possibly a bad sensor or something else with the EGR system.

 

Thanks for the info. I checked the air system quickly tonight and it seems that the pump is sucking air through the filter fine. Where does the air get pumped to the cats? How would I check if the O2 sensor is still good,the wiring to it looked intact.

 

Must be a 5L engine truck? I thought 5.8L trucks did not have the AIR system in 1996. There is an idler pulley where the air pump used to be.

Since yours obviously has the AIR injection system the flow is controlled by the TAB/TAD solenoids and valves.

The solenoids are located near the coil:
They a electrically actuated vacuum solenoids.

Items A and C are the TAD and TAB respectively.


Your 1996 may have them in slightly different locations. Check the vacuum lines are intact and not cracked.

As far as the O2 sensor code it could be a bad sensor, they do have a finite life. Inspect the outside for signs of oil, grime, etc. That can affect the O2 sensor output. I believe that O2 sensor is used to measure/calculate converter efficiency. You could have a converter going bad too.

 

Tried to track some of the problems down today. Checked all the vacuum lines and it looks like the previous owner filled a crack in one with silicon, could this be the issue? It seems to be fully sealed. The rest of the lines look intact. As for those diagrams everything is the same except for c on diagram two. There is nothing there, the only thing around there is this.

It is behind the alternator and is in connected to the air pump system. Is this c?