I have a 97 expedition 5.4l and i am having the trouble code po401, but i have read that model yrs 96-2001 can have up to 2 system not ready codes and still pass emissions, so im wondering if i was to get a scanner to clear this code, would only one system not ready code show up on emissions and i would be able to pass, i live in ga, and im not even sure if thats the case but thats what ive read. If that is possible what scanner is best that is readily available at the local auto parts store? I saw advance carries actron and one that is capable of clearing codes is like $180, is that a decent one for the price or can i get one just as good for less dinero? Thanks in advance.

 

Why don't you just fix the problem? P0401 is common, you have an EGR issue, most likely a new DPFE will fix it.

 

Well i already took off the egr valve and cleaned it and also took off the throttle body/upper intake and cleaned out the port holes to the egr valve and i drove 10 miles and check engine light came on but i'm thinking it could be a different code and just wanted to know about clearing codes and a good scanner to purchase. Does anyone have any suggestions about a good scanner from autozone or oreilys, or if clearing one code so only one system says not ready if it will pass emissions?

 

As I said, the most common cause of a P0401 is a bad DPFE (or cracked vacuum lines going to it), *NOT* the EGR valve itself.........

 

Pay attention to what glc is telling you, jdunwidd. He's trying to save you some money and get you past the emissions check too! Even if you WERE able to clear the code, it would probably come right back if the underlying problem is not repaired.

- Jack

 

Trying to cheat the system is VERY tricky. When you clear codes, you computer resets a count that says the vehicle has been driven X miles since the last code clearning. You have to go at leat 5-10 miles before your computer resets itself, which is why the code will come back after you clear it- because it's reset and reading properly. The DMV knows if you cleared the code right before you go there, your computer will rat you out! ^_^

 

.......i have read that model yrs 96-2001 can have up to 2 system not ready codes and still pass emissions....

I believe this is correct, as I have seen at least one system not ready on my own emission report.
As your mechanical issue has been diagnosed and is easily repaired why not fix it anyway?

 

It depends on the state. In IL, you cannot have *ANY* stored codes, and the P1000 must be gone.

 

I am stumped, I have cleaned everything, egr suck test performed caused stalled engine so its operating correctly, replaced dpfe sensor, Mil lamp on again, I read you can check the vacuum wiring harness with a mighty vac, how exactly is this performed, going to find out whether i can pass emissions with one system not ready as when i use scanner after clearing po401 it says only egr system check incomplete, anyone know where these regulations are found for Ga?

 

I found this on the cleanairforce.com website http://www.cleanairforce.com/docs/readiness.pdf, stating "If enough monitors have not completed the check of the emission
control system by the time a motorist presents a vehicle for inspection, the vehicle’s on-board diagnostic (OBD) computer will
not be “Ready” and will fail the inspection. For example, 1996 to 2000 model year vehicles will fail if three or more monitors are
“Not Ready” while 2001 and newer model year vehicles will fail if two or more monitors are “Not Ready.”

Thought I would mention this just in case your from Ga and having problems like me.

So now I'm guessing if just the egr system says incomplete after checking with scanner, then I can still pass emissions.

 

Only problem with that is - what happens if the EGR system DOES complete the readiness testing and the fault DOES trip the CEL before your inspection is complete? That's a fail.

 

Right, After clearing the code multiple times, it would take between 15-20 mi. for the mil to light up, but luckily the emissions is 2 mi down the road, but i realized after clearing the code i went and looked at the monitors and it also cleared 2 for the oxygen sensors, one for the evap., and one for the egr, so thats 4 incomplete systems and wouldn't pass, now im back to trying to test the vac lines with a mighty vac, and checking the evm voltage, can anyone explain the procedure for doing those. Thanks for everyone's replies, it's greatly appreciated.

 

Could you please post all the exact codes by number?

 

It IS getting a bit difficult to follow, isn't it?

- Jack

 

it is only one code p0401, i was saying if you clear this code with a scanner it resets 4 obd2 systems as mentioned above, I am still stuck on this code and im not sure how to move forward, i have taken off the throttle body/elbow and cleaned the ports, replaced evm solenoid, replaced the dpfe sensor, checked and made sure the egr valve was working by applying vac and it stalled the engine so that is working, now i assume i need to check the vac lines with a vac tool but im not sure where to begin. when i replaced the evm solenoid i was curious to see that the green vac line on top didn't totally butt up to the solenoid but was off by maybe a cm or to, i think i am going to check that connection but i don't specifically know how to vac test the line, can anyone help me, i appreciate your reply in advance, I am frustrated and confused at this point.