Scotty I can't get the O2 or Cat monitors to clear. no error codes for either. My scan tool does not show live data so its hard to tell what's going on with the O2 sensor. A while back I changed the bank 1 downstream O2 sensor because the heating element was bad. Some people have suggested that the make of the O2 sensor I replaced could be the problem. Also I do get a 0446 once in a while but I don't think it related to the other two monitor not clearing. Inspection is coming soon !!
I would Greatly Appreciate any insight into this problem and I love your Videos
Thank You
Ron
2002 blazer 4.3, 4 door, 143k miles
I replaced the down stream sensor with a OEM and still O2 and Cat monitors wont clear. tried disconnecting the battery to clear ECM and same.
any other Ideas
I just want to thank everyone and anyone who helped me fix this problem. Special thanks to Scotty for use of this site for feedback and Chuck Tobias for the above graph showing o2 voltage changes it helped a lot. Luckily I have a neighbor that has a ODB scanner that shows O2 voltages and it proved that the cat was working properly. I found a video on line the showed the relationship between the fuel sensor in the tank and monitors clearing.
( https://www.youtube.com/watch?v=c0TmOCNyvJ0 ) it also involves the evap monitor not clearing. Anyone who owns a Chevy truck knows that the fuel gauge can swing wildly or stop working all together which can stop the monitors from clearing. I changed the tank fuel pump and sensor and one by one the monitors started clearing starting with the O2's. then the cat which gave me a green light and allowed me to get the truck inspected
This saved my a lot of $$$ and kept my blazer from the bone yard.
THANK YOU AGAIN and keep up the good work
Ron Russo
West Babylon, N.Y.
thanks for reporting back! Hopefully it helps somebody else too.
Some people have suggested that the make of the O2 sensor I replaced could be the problem.
It could be especially if you use non-OEM O2 sensor. Always use OEM oxygen sensors.
I replaced the down stream sensor with a OEM and still O2 and Cat monitors wont clear. tried disconnecting the battery to clear ECM and same.
any other Ideas
Your 20-year-old catalytic converter could be bad. That's a condition the I/M monitors are designed to detect. What does live data from the O2 sensors look like?
my scan tool does not show live data is there any other way to check the catalytic converter, the truck has plenty of power so i know its not clogged
what other way could it be bad ?
It can be bad if the catalyst is worn out and simply not doing its job any more. Doesn't have to be clogged for that. Are you sure about not having live data capability? Even the cheapies these days can display and record live data.
https://www.youtube.com/watch?v=KGpMzdEO5KY