so my new to me truck decided now was a good time to have a check engine light come on. So like I always do in this situation I go the cheapest route(free) and run down to Oreilly auto parts and have them scan the DTC's to see what they can come up with. Here they are…

-p0443 evap vapor management valve circuit malfunction- stored
-p1409 EGR vacuum regulator solenoid circuit malfunction- stored
-p0401 insufficient EGR flow detected-I believe this caused check engine light
-p0411 AIR system incorrect flow detected-stored

Now while I am pretty handy with a wrench, understanding how some of these systems works still eludes me. The auto parts guy recommended i check my vacuum lines with a spray bottle of soapy water while the truck was running. I did that but Im not sure if I got all of them. I only saw the top of two that were connected to what I think is the EGR valve. Does anyone have any ideas or fixes to these issues or am I stuck buying all new parts and going from there? Thank you in advance.

 

What year and engine?

 

Sorry I completely forgot 96 4.9l

 

That was a waste of soapy water (which won't do anything useful for diagnosing the actual fault). Now you know why that guy is a parts drone, not a technician.

The first two are electrical faults, probably an open circuit. Check the canister purge valve (usually has a green service cap on it) and the EVR solenoid (follow the vacuum line from the EGR valve back to it) electrical connectors for damage. Verify +12V on the red wire of each (ignition in RUN, engine off). Check the connectors for corrosion, bent or pushed pins, etc.

I'd clear up those two electrical problems first, then reset the PCM (remove KAM power or neg battery cable) for 10 minutes), then drive the truck normally for a few days to see what might pop up.

The EGR flow is often a bad DPFE sensor, but, since you have a circuit fault for the EVR, the electrical fault takes precedence for correction.

Sorry, I'm not up on the AIR system as none of my vehicles have ever had it so I've never learned it.

 

Awesome thanks for the help I'll do that and let y'all know the outcome

 

@TuffD...I have the same year truck and same engine...I also had issues with the check engine light coming on, and staying on...after numerous "fixes" I took it to my mechanic who went over it with a fine tooth comb. He found that both 02 sensors on the cat conv were giving false readings to the on board computer, which triggered the check engine light. He checked the 02 sensors and got good readings, he told me to just unhook the battery when it happens, and then wait a min, then hook the battery back up. It works- the check engine light wont come on again for another year at least.

 

Your experience has nothing to do with the OP's situation.