So I failed my emissions test yesterday. Everything passed except the carbon monoxide (16.157, max allowed is 15.00). My catalytic converter is 2 years old and the plenum is fine. About a year ago the check engine light came on, code 0441-Evaporative Emission Control System Incorrect Purge Flow. I replaced the gas cap and the purge solenoid and inspected the charcoal canister and the lines going to from. Everything appeared fine. About a week after replacing those two items, the check engine light went out. It came on again several months later, same code, but went out again shortly after. The check engine light hasn't been back on for about 7 months now.

So, my question is, should I go back and look at the Evaporative emissions system or start elsewhere? I currently have just over 3,000 miles on this oil change and I read somewhere changing it just before the test can help as it burns about 1 quart every 5000 miles. Would swapping out the forward oxygen sensor help?

 

That's your cat being inefficient. Depending on how old the O2 is, it might help.... Changing the oil just before you go in helps as well. Another tip is to make sure the cat is HOT when you go in for the test. Drive at least 20 miles before testing.

 

A possible thing is to move your truck to somewhere that doesnt have emission. A little extreme but would work :P

 

You must live in northern colorado because i live near colorado springs and they dont do emissions here ?

 

Thanks HeyYou. After talking with a few more people, I'm thinking this might just be a fluke since the other numbers were well below the max limits. I'm gonna change the oil and take it back in for the free retest. When I got to the emissions place the truck was at operating temp, but I'll take it out on the highway before I go to make sure the cat is hot before I run over there. Also, on the inspection report it mentioned that the main cause of failing Carbon monoxide is the engine running too rich. Earlier that morning I had the battery disconnected and I think I reset the pcm. So I'm also thinking may have had something to do with it as well.

Getdown78, yeah I live in the Denver-metro area. Only certain counties require emissions testing in Colorado.

 

How old are the 02 sensors ?. If they are the original 02 sensors with over a 100.000 miles on them, then there bad and need to be replaced

 

Mine wouldn't pass being it has no cat and dummy O2 sensors ! lol