well my mom drives this and she said she just heard a clicking noise coming from one of the tires but they dont know which one..and my fuel gauge is bad..it wont read the amount of fuel in there. how much does cat converter cost for these things??? and the car has about 160k miles on it. how much do BCM's cost for these? i know alot about diesels but nothing about gassers my dad knows gassers but nothing about diesels..thanks for your guys help! i need these fixed in a month

 

bump for some more help....

 

1st off, I'd head to auto Zone and get the CEL codes read and CLEARED, then see what you get again. Repeat. Start picking away at the issues. The p0420 could be the rear O2 sensor, but if the cat' hasn't been replaced yet (once or twice) it's most likely the cat. Cat should cost about $200-250 to replace, less if you do it yourself. And unless the O2 sensors die completely, the probably won't throw any codes other than the p0420. Has the O2 sensor been replaced?
Before replacing the rear hub, take apart the connector and clean it good. Most likely that's the problem.
Also, you might try disconnecting the battery for a bit and trying again. Check the BCM connection.
At this point, Google is your best friend, along with this thread.

 

When considering a cat converter keep in mind most aftermarket cats aren't as good as oe, a P0420 can still set if the cat is of poor quality. And a used cat is worth about $80 if it's the gm original or a gm replacement . And it's not correct that an O2 sensor will only set codes if it's completly dead so don't assume that they are okay. There is no such thing as a code for the coolant thermostat, maybe for the coolant sensor but there is still just a plain thermostat in every gm car or truck. If the you do read any code book or a reader and it says it's a coolant thermostat code it's wrong.
Fix your temp sensor problem and probably the cat, clear the codes and I agree see if any come back if not just keep driving it if everything is working fine.