My car is gutted of all that BS. I was still getting the secondary code. I fix that by plugging the line that has the solenoid valve on it, I stuck a ball bearing in the line and put it right back on. It is the line right next to the vacuum line for the brake booster. I think it is for evap system but don't really care enough to trace it down. Good luck, hope this helps.

 

I had this same issue a while back, my diverter valves were bad.

 

Good luck with that......

 

just got my car back from champion for the 0491 and 0492 codes, turns out it was the changeover valve which was replaced a year ago march. Maybe you should check it out

 

You may be able to, in some states you have to show that you spent some required amount of money to attempt to fix the problem (usually a few hundred dollars) and you get a waiver for a year. I had an 87 Carrera that almost required it, but ended up finding the problem. Good luck.

 

I had those same codes and it turned out to be one of the diverter valve tops had come loose.