1999 GMC Sonoma fuel mileage

Ok what you have here is a code that now can not be fixed. The code is a Cat low flow code. So now that there is no cat the truck is running on preset information not on sensor information. The only way to make it run right again is to put a cat back in it. Now the down stream O2 sensor which monitors cat flow is seeing to many emissions because the temp in the exhaust is to low because of no cat so it just can't run as it should. So tell me why did you remove it in the first place?

[quote:d9aefdc71d="racefan966"]So tell me why did you remove it in the first place?[/quote:d9aefdc71d]

I removed it because it was rattling the piece inside had broken off. there is no way i can put another one back on at this point the flanges are cut off and it would be a mess. is there anything else i could do?

You need to replace it inorder for the computer to work as it should with the sensors. There are universal ones that can be bought that don't use the flanges and cost less too. I am sorry for the bad news but until the cat is replaced and the codes are cleared after that you can't get it run and get the mileage it should.

ok thanks

Let me know how it ends up ok. If there are any more problems when it is back to correct let me know and we will go through what ever tests may be needed. Thanks again and have a great day.