code 0157 and exhaust smells like rotten eggs???

**JRENIGAR** · 06-08-2010, 11:40 AM

Ok first off I have a 99 ls1 car and my wife had an 04 yukon with the 5.3 so I hope I can ask this Question without getting bashed. The yukon is giving the ole 0157 code and the exhaust smells bad. My Q is would that be a bad converter or maybe a bad o2 sens??? Any help appreciated.

**sunsetorangess** · 06-08-2010, 12:26 PM

Since that code is Sensor 2 or Aft cat i would lean towards your cat being bad or clogged.
How many miles are on the truck? Any loss in power?
Dont worry about getting bashed lol, the only stupid question is the one someone doesnt ask...
J

**JRENIGAR** · 06-08-2010, 01:04 PM

Its got 101k on it and Im not really sure about a loss in power but it feels like its kinda sluggish. I dont drive it verry much mostly my other half does.

**Cutlass** · 06-08-2010, 06:21 PM

Its cheaper and easier to slap a new o2 sensor in there, clear the code, and see what happens.

**Brads_BadZ** · 06-08-2010, 06:44 PM

Dont waste your money on anything yet. I would either beat the crap out of your cats or remove them if you can and clean them out. The only other option is replacing them which can be rather costly. If you are getting a rotten egg smell that is a tell tell sign that your cats are bad or going bad. I guess if all else fails you can try replacing or cleaning your sensors before you shell out the money for new cats but I would try all of this in order and see where it goes from there.

**Cutlass** · 06-08-2010, 07:04 PM

Originally Posted by Brads_BadZ

Dont waste your money on anything yet. I would either beat the crap out of your cats or remove them if you can and clean them out. The only other option is replacing them which can be rather costly. If you are getting a rotten egg smell that is a tell tell sign that your cats are bad or going bad. I guess if all else fails you can try replacing or cleaning your sensors before you shell out the money for new cats but I would try all of this in order and see where it goes from there.

I don't about that. If you gut the cat, you'll still have an SES light for the cat not working. I wouldn't suggest that.
Rotten egg smell isn't necessarily a bad cat. Actually usually it isn't. Usually its bad gas and the smell will pass after a couple tanks of gas.
P0157 is almost always an indication of a bad O2 sensor. Its actually highly unlikely its a bad cat

**Wesman** · 06-08-2010, 07:40 PM

Originally Posted by Cutlass

I don't about that. If you gut the cat, you'll still have an SES light for the cat not working. I wouldn't suggest that.
Rotten egg smell isn't necessarily a bad cat. Actually usually it isn't. Usually its bad gas and the smell will pass after a couple tanks of gas.
P0157 is almost always an indication of a bad O2 sensor. Its actually highly unlikely its a bad cat

Agreed. If the one of both cats are bad, the code will almost always be P0420. That code is set when the secondary O2's are switching too similarly with the primary O2's, indicating that the cat is not working effectively.

P157 is defined as O2 sensor circuit low voltage bank 2 sensor 2, which is typically a bad O2 sensor.

I would replace the O2, run some seafoam through the engine, and take it on a nice long drive with some fresh top teir 93 octane.

**Brads_BadZ** · 06-08-2010, 08:17 PM

I guess your right. If you gut the cat it will throw a code. I wasted money on some rear o2 sims before i got my tune and i didnt have any issues with them. It did get rid of the code so I guess your right about the 0157. Although from my past experience the rotten egg smell has usually been from a bad cat(only once from bad gas). I have seen sea foam or a similar product help with that issue. +1 Wesman.

**JRENIGAR** · 06-09-2010, 07:46 AM

God advice from all. I dont really care if the ses light is set from removing cats as we dont have any tests here, but theres no sense in removing them if thats not the problem. I will try replacing the sensor and go from there. I just thought if the sensor was bad it would smell rich and not like the rotten smell Im getting but I guess its a toss up. If the sens dosent fix it I can gut the cats for free and go from there. Thanks...

**JRENIGAR** · 06-13-2010, 10:57 AM

update!!! I removed cleaned and swaped the rear o2's and have put 400 miles on the vehicle since and no codes and no more bad smell. Wierd but I'm happy... BTW I cleaned the sensors with regular carb cleaner in a spray can.