Hello folks. Is there a reader/instrument to read the Co in the exhaust?
My truck failed the emisson test today. it was way to high

 

there is, but they are fairly expensive. Carbon Monoxide tells me that the cat is starting to fail. I know thats a fairly generic response, but that is the only job of the cat...to take the noxious gases that come into the cat and make different, non-noxious gases when the metals in the cat atomize from heat. If thats not happening, the cat is failing. You could also be running extremely rich.

Someone please chime in if I am wrong.

 

You would need a 4 or 5 gas analyzer...big bucks, in the thousands lol. I'm surprised that there's no check engine light or codes. Any idea if the HC's (hydrocarbons) were over also? If so, I'd be looking towards incomplete combustion (misfire). If HC's were OK and all you failed for was CO, you're either running rich or have a bad cat as 03 BLACKOUTSSS mentioned. What year is your truck? If it's 04 or older, you have a fuel pressure regulator on the driver's side fuel rail that could be leaking and causing the rich condition. Is the tune up current? (plugs, filters, etc)....some of the basics to consider first. If you have a scan tool or access to one, you can monitor your Fuel Trims and main and sub O2 sensors to see if you actually are running rich or if you have a cat that's not doing it's job.

 

I will wager a shiney nickle that the HCs are high, too. Maybe it is not reported until it exceeds the fail level.