01FormulaTA

iTrader: (20)

Ok well I just got my car 2 weeks ago and it was fine('02 Z28 M6), I got it from the original owner w/ 37k miles and he told me the only problems that he had with it were that one of the cats went bad and he had it replaced under warranty like 2 months ago, he showed me the receipts and stuff. Anyways the cars SES light came on today so i went to autozone to have the codes pulled and they were as follows: P0420 - catalyst system efficiency for bank 1 is below threshold(Im assuming this means a bad converter, this is also the same one he had replaced), and P0175 - the fuel system for bank 2 is too rich. I thought the car running rich might have caused the cat to go bad but what doesnt make sense is that they are on opposite sides.....the P0420 is for the drivers side, and the P0175 is for the passenger side.....only mods on the car is a SLP lid and K&N, I checked the MAF and tb and they had no obstructions. So what should I do? Why would my car be running rich? How do I fix it? bank 2 is cylinders .2.4.6.8. so should I pull the injectors and have them checked? suggestions would be great, i need help, this is my dd and the search is down.....

-Chris

01FormulaTA

iTrader: (20)

someone has to have thrown a P0175 code before??? C'mon guys I need some help to get this resolved

01FormulaTA

iTrader: (20)

TTT....need help with P0175

01FormulaTA

iTrader: (20)

TTT....wow not getting to much help? did I post in the wrong section?

LiENUS

Likely bad o2 sensors, both fronts and rears.

Travose21

iTrader: (22)

bad cats and o2

LiENUS

Cat was replaced its unlikely its bad already.

01FormulaTA

iTrader: (20)

yes technically the code says: "catalyst system efficiency for bank 1 is below threshold" so hopefully its just not operating at full capacity b/c the car is running rich, I am going to replace the front O2's this weekend and reset the PCM and we'll see if that helps, ill keep you guys updated.....

01FormulaTA

iTrader: (20)

ttt....

01FormulaTA

iTrader: (20)

ttt....

prostreet1967

iTrader: (1)

the p0420 code could be either a o2 or converter it would be the downstream o2 if it was bad best way to check is to graph that o2. as for the p0175 it could be the upstream o2 sensor or a leaking injector

brad8266

iTrader: (23)

Replace all O2 sensors first.

01FormulaTA

iTrader: (20)

ok guys so I replaced the o2's and wasted $200 b/c it did nothing, both codes are still there after replacing the sensors and resetting the computer.....so I guess my next question is how do I check the injectors???

01FormulaTA

iTrader: (20)

ttt...

01FormulaTA

iTrader: (20)

ttt...

01FormulaTA

iTrader: (20)

ttt.....wow im really looking forward to heading to the Stealership to have this diagnosed

Sneakyws6

The cats are now covered for 10years/120,000 miles under a upgraded factory warranty.

If after resetting the ECM and doing a drive cycle and the P0420 cde has came back then more than likely the cats could be bad again. Take it to the dealer under that code and have them check it out agaon.

01FormulaTA

iTrader: (20)

ok well the SES light went off but I had autozone check it and the codes are still there, so whats that mean?

Sneakyws6

They need to clear the codes, then you need to reset the ECM by removing the under hood fuses and then drive the car and put some miles on it to make sure the problem is gone.

Turn the key on and in each of the under hood fuses blocks on the drivers side remove the PCM BATT fuse and PCM IGN fuse. Leave out for a couple of minutes. then turn key off and replace. Turn key on and start the car. It may hunt for idle for a bit. You can shut it off and restart and it should restart normal. Take it out and rive cycle it, if the cat issues is still there it will only take about 50 miles or so for it to show up again.