Novice here on exhaust systems here, so bear with me :: I've had to replace both my oxygen sensors 2 times in the last year; front one once, the back one twice. Is there some other issue, bad exhaust system etc. that I should be looking at? I used NTK sensors. Thanks!

 

What you burning for fuel?

 

***Year, model, engine and mileage needed***
Would need to know why they were replaced the 1st time. (don't say because "that's what the codes said")
If you can remember the actual code #'s then and now, we can probably help you.

As far as what could be killing the O2 sensors. Does your car burn oil ?

 

Yes, and does your car burn coolant? A head gasket leak might not seem like much if you only have to top up the coolant once a week, however that can kill your catalytic converter and the O2 sensors will set codes as they should, but they are just reporting there is a problem.

 

Coolant will kill an O2 sensor that fast, oil not so much.

 

2006 HHR LT 207750
Actually the first time because of codes, and my mechanic told me, I did them myself
P0136 P0137
She burns a bit, I use about 3 quarts in between oil changes as about +/- 5000 mileage

 

just regular gas

 

No she uses no coolant

 

Did the same repair facility replace all the sensors? If do, find a new place.

 

Both of those codes refer to the downstream 02 sensor. If those are the only codes, then, as Greg suggested, find a new shop.

Since replacing the sensor didn't fix it, I would suggest looking for an exhaust leak. Could be in the flex pipe, which has probably broken due to a broken or worn out front engine mount.