I'm getting 2 engine codes for my 2 cats which I found out where hallowed out, and a code for the secondary air pump. I just had it at a mechanic and they tested the check valves and pump, and all tubing. All of which work fine. They think the code is coming because of no resistance since the cats are hallowed.

Are the rear 02's anyhow related to the air pump in the computer?

They said they would clear the code and immediately when the car would turn on the code would come back up, they also said the air pump begins pumping right off the bat which its not suppose to.

Any help?

 

The rear 02s and the air pump circuit are unrelated. The air pump is supposed to work upon initial startup to reduce exhaust emissions. Would you happen to know the code number for the AIR issue?

 

I have this exact same problem the SES light came on and I took it in and the mechanic said the air pump was going out. I cut off my cat about a month ago. Does your car have a vacumn cleaner sound coming from the front when you start it?

 

Depends on what you mean by vacum cleaner, but it sounds like the fans are on high but they are not.

 

Get the exact code for the AIR pump. There are two related to actual air flow to the two banks of the exhaust, measured by the PCM looking at the O2 sensor readings when it cycles the AIR pump on and off, and another code for a faulty electrical circuit on the AIR pump. None of those codes can be caused by lack of a cat.

The noise at startup is probably the AIR pump running, since it can rust up and start to sieze up. That's when the fuse usually blows, and you get the code for the electrical circuit.

There is a factory recall for the AIR pumps on the 95-97 LT1's.