Your assistance is appreciated

We have a couple of issues:

1. PO138 Code - 02 Sensor high voltage - Bank 1 Sensor 2.
2. Exhaust noise that seems to come from under the hood.
a. One person suggested it was the catalytic converter assembly and should be replaced.
b. Another person suggested it was the exhaust manifold and the exhaust manifold should be replaced.
3. Exhaust System noise (rattling) toward the rear of the vehicle.

Should I plan on replacing the O2 Sensor down stream of the catalytic converter tomorrow as planned or
Could this error code be caused by an exhaust leak and i should be replacing the Catalytic converter assembly or exhaust manifold?

:banghead:

Thanks for you help.

http://www.obd-codes.com/p0138

What engine/transmission and how many miles?

Any restriction in your exhaust? Has your mpg gone down recently? Often when O2 sensors fail, they fail in the rich position, dropping your gas mileage.

I'd definitely fix the exhaust leak under the hood, and probably replace the O2 sensor.

Thanks for your help

Straight 6, automatic transmission w/ 150K miles

I don't know of any restriction(s) in the exhaust. What could/would restrict the exhaust?

This is my daughters vehicle and she hasn't been checking mileage. so we're unsure.

What would be my best approach to determining what/how to fix my exhaust leak? How do i better determine where this noise is coming from to know what needs repair/replacement?

Thanks

Some of the V8 models had an issue with the catalytic converters from around 95-99 or so, but since you have the I6 it's all good and probably not an issue.

As far as mpg, next tank have her check it; and if it's less than maybe 16 in town and 20 hwy, then it's likely to be the O2 sensor. Typically people have reported mileage in around 12 with a bad O2 sensor.

As far as the exhaust leak, it's likely the exhaust manifold where it joins the engine. Have a look under the hood while it's running ant try to locate the leak more precisely -- it might be tough to find but is fairly apparent once located. Look for a dark area, or moisture where it should be dry. Hard to describe.

Thanks for you insight,

After a little prying my daughter thinks she's getting 14 city 17 hwy. So we've purchased the O2 sensor.

Yesterday I crawled under the vehicle and discovered an exhaust leak at a joint between what I'd call the cat assembly and the exhaust system assembly. So we've purchased and installed a new pipe clamp (to replace the piece of crap OEM installed), suspension system clamp (to support the exhaust system towards the rear of the vehicle and exhaust system joint compound (hope this stuff works).

Today I intend to install the new O2 sensor. Reset error codes and hopefully all our problem(s) will be solved. If not I'll be back later today for some additional assistance (I believe if the joint compound works we should be good to go).

I'd like to THANK YOU AND THIS FORUM AGAIN it provides the insight that people like me get the confidence to do these repairs ourselves.

All of us weekend warriors need to pass this website to everyone. I have and will continue to tell everyone i know.

Fredjacksonsan not sure how you answer all the questions but I really appreciate your insight and assistance.

Thanks again!!!!

More than welcome. I've owned a GC for more than 4 years and have done a lot of reading, is all. Glad to help. Let us know if this fixes everything.