o2 sensor question

**Justin23454** · 01-18-2012, 10:59 AM

all but 1 of my o2 sensors are setting off codes, could this be because I have LT headers and Gutted cats? (no computer tune yet) OR should I replace the front 2? (for some reason 1 of my rear ones is not being set off but the other is and like I said I got gutted cats so I would think both would set off)

Question is, should I just replace the front 2 to see if it fixes the front problems. (I know I gotta buy the Corvette ones because the ones for the T/A wont reach with the LT's but can anyone remind me which they are, I have not bought o2 in awhile, thanks)

**2000dreambird** · 01-18-2012, 11:12 AM

Originally Posted by Justin23454

all but 1 of my o2 sensors are setting off codes, could this be because I have LT headers and Gutted cats? (no computer tune yet) OR should I replace the front 2? (for some reason 1 of my rear ones is not being set off but the other is and like I said I got gutted cats so I would think both would set off)

Question is, should I just replace the front 2 to see if it fixes the front problems. (I know I gotta buy the Corvette ones because the ones for the T/A wont reach with the LT's but can anyone remind me which they are, I have not bought o2 in awhile, thanks)

you need to have it tuned, and the rear o2's deleted. You problem is most likely due to the hollowed out catt. the point of the rear o2's are to report when your cat has gone bad. why your only getting it on one side and not the other i have no clue.

**Vexzer** · 01-18-2012, 02:54 PM

There's a thread about a wire mod that allows you to keep standard O2 length's. It shows how to reorganize the stock wiring for the rear O2 sensor for front O2 use. It's on this or that 'other' LS1 forum. The rear cat's only monitor cat efficiency and have no performance purpose -they are for emission control purposes. With gutted cat's, the only way you will get away from the CEL's is for a tuner to disable the secondary O2's, along with the CAGS, VATS, AIR, speed limiters, and some other stuff that has no performance -just maintenance & emission purpose.

**pajeff02** · 01-18-2012, 06:13 PM

The sensors with the long harness are the Bosch P/N 13111 units. I run those on our car with LT's and have had zero issues. Don't let the parts counter guy tell you anything different -- we've had a few members on here who went for the 13111's and ended up buying something else. As already posted, your rear O2's simply tell the PCM if the catalytic converters are working properly. The best thing to do is have them "tuned out" so that their error reporting will not trigger the SES light. O2 sensor performance degrades over time and I would definitely replace anything with 75,000 or more miles on it. Other common problems are cooked wire harness from the exhaust heat or contact, corroded connections, or burned out heater circuits in the senders.

**0rion** · 01-18-2012, 10:17 PM

how many miles on the sensors you have in there now? If you're in the 70-80k range I would replace the fronts anyhow. The rears are because of the no cats thing and it depends on what the code for the front is if it's header related. Very easily could be but without knowing the code it's hard to be positive.

**Justin23454** · 01-20-2012, 07:10 AM

ok, ill go back and get the code to make sure what it is. I have less then 10k miles on the o2's though. But now that I remember I DID have those in when I ran through water that blew my eninge... So it was soaked with oil/water. im just going to get new ones and see if that atleast fixes the front, and once I do that (and it does fix) im gonna send it to frost to tune it.

**Justin23454** · 01-20-2012, 07:40 AM

everything says they wont fit my car, but they look just like the ones I have on now! ill just buy them I have faith in you pajeff! One question though, is there a diff o2 for front and back? They all say for after cats.

**0rion** · 01-20-2012, 08:50 AM

those will work....they're actually vette rear sensors. They're all the same though....the difference is in the length of the harness. I run 13111 sensors on mine in the front so I don't have to run extensions.

**Justin23454** · 01-20-2012, 09:29 AM

Originally Posted by 0rion

those will work....they're actually vette rear sensors. They're all the same though....the difference is in the length of the harness. I run 13111 sensors on mine in the front so I don't have to run extensions.

ok, thanks