Anyone happen to know the voltage tolerances for the pre and post cat o2 sensors? My car is throwing P0136 (points to post cat), but I'm having all symptoms of precat o2 sensor failure/degradation.

 

What symptoms are you having?

Catalyst problems can also trigger post cat codes.

 

High and Rough idle (usually from 1200-1700 RPM), terrible fuel economy (average about 19 mainly highway), and black exhaust tips (can smell richness also)

 

I would start looking for vacuum leaks, is the air filter clean? How do the spark plugs read?

What are your fuel trims?

 

Had a leak down test done that came back negative. Having the codes P0136, P1242, and P0507. Thinking for 1242 that the MAP vacuum tube is cracked or something. Will have to break out the OBD and get back to you on the readings

 

Did you want readings at idle or driving?

 

With those codes I'd say you've got a vacuum leak or a stuck BPV.

 

BPV was replaced with a DT about 1k ago

 

Sensor 1 was jumping all over the place at idle, from about .15v to .76 or so. Sensor 2 was within .01v the whole time.