My brother has an 04 Chevy Express van that I am trying to help him pass an emissions test in Georgia. Been 7 or 8 times and it keeps saying that 2 sensors are causing the computer to stay in an open loop. We replaced the computer because the tech said it was bad and that didn't help. Now they keep telling him to keep the gas tank between 1/4 and 3/4 and drive for long distances at steady speeds. That has gone on for 3 months now with no new results. The 2 things it keeps failing is catalyst and evap. We are at a loss and the dealership is not helping at all. Gotta be a solution or a way around so he can get legal again. The van runs great and no noticeable loss of mileage or anything. Thank you guys for any help.

 

I assume the bad sensors have been replaced? What are the trouble codes?

 

Your the first to say replace the sensors. The techs keep saying they need to reset. I dont have any codes, the emissions test just says catalyst and evap fail. When the computer was installed it was fine with no codes and still have no lights on.

 

Has the cat converters ever been replaced? What about the 02 sensors?

 

neither one has been replaced but neither is throwing a code.

 

So the emissions testing equipment is saying fault but the vehicle odb system says there is no codes.....that sound like bs on the testing facilities part.....Can you challenge the emissions test? Can you produce a clean bill from the dealer to the test facility?
Thank god we did away with our Aircare system.....

 

you need to print out and follow the drivecycle for the cat and evap monitors. the monitors will not complete until this is done. when they run, they will either pass, or fail and set dtc.
Since the conditions to run the monitors are not being met....you are in a holding pattern.
I assume all other monitors have run and passed. The cat monitors need the 02 monitors to run and pass before they complete. the evap monitors won't run if the fuel level is above 3/4 or below 1/4 full.

 

Drive Cycle Issues: What to Do When the Drive Cycle Won't Complete

does this help?

 

Canucklehead, sad thing is its the stealership telling us this. but thats 2 places its failed. Were going to try the driving cycle first and then if that doesnt work we will try the other. thanks guys

 

Good luck.