I have a 2000 MN6 coupe with a Blackwing filter and ported throttle body and mass air sensor. It has always run fine with the blackwing for the last 3 years. This winter I cleaned and re-oiled (I thought lightly) the filter. Soon it began to show IAT codes and at the same time after taking it out of winter storage the active handling warming up came on every time I started the car (this hardly ever happened in the last 5 years and it always goes off after warmed up in about 15 minutes). I drove it for a few weeks (to breath in the air filter oil) and got a new IAT sendor. The IAT codes still keep coming but the only occur after a sustained run (say 20 miles) then I have to stop at a signal and idle for 1-2 minutes, then just before I take off again, the IAT code comes usually accompanied by a slight roughness in the idle.

Any thoughts will be apprecated, the check engine light is so annoying.

 

I just dealt with this issue myself and resolved it on Friday.

The active handling system uses the IAT to tell it how cold it is outside so it knows what kind of weather conditions it's dealing with. When the IAT connection is dead it the active handling system thinks it's -38-degree's outside. There's nothing to 'warm up' on the active handling system, it's just waiting for all of it's data to determine it's mode of operation for the current weather conditions. Since it can't see the IAT it's simply telling you it's not ready to activate.

There are really only three problems that it could be. A bad connection at the connector that plugs into the IAT sensor, a bad ground, or a bad connection at the PCM. Since the symptoms appeared after you removed the connector to clean your filter I'd guess that you have a bad connection at the connector as I did. My symptoms appeared after I installed my Callaway Honker.

Your GM dealer sells this connection for about $28. It's a new connection with a 10 inch lead wire on it. Part Number 12102620. My local dealer had one. Cut the wire to the IAT sensor an inch or so from the end of connection and splice and solder this new piece in. I put shrink wrap over the soldered connection and then electrical tape over it and it looks like stock. I started the car and went for a drive. No warm up and no CE light. After about 100 miles of driving I am code free and CE light free.

If you really want to know for sure it's the connection go to page 11 of the sticky on the electrical ground issues on the C5's in this section to learn how to check the voltage at the connector.

Questions, let me know. This should be everything you need. If you want more, search on codes P0113H and P1111H.

Kurt