93transam1234

Ok i hooked my car to a scanner and was waching the o2 readings. While at idel the left one was betwen 120-600
and the right one would stay right at 60-90..while driving they would both read from around 190-800...does this sound about right

I am putting on LTs and need to know if i need new o2s
thanks for the help guys

Injuneer

Depends...

Start the car and both O2 sensors will read about 450mV. Slowly, over a period of about 2 minutes, they should drop to near 000mV, at which point the PCM enters closed loop, and the O2 readings will start to oscillate, each side independant of the other, between maybe slightly under 100mV to slightly over 900mV. If either sensor stays pegged at a single value, or even in a narrow range at any point in closed loop operation, there is something wrong.

Unless you have a logging scanner, its hard to see exactly how the O2 mV's are reading. They are changing almost 10 times per second, so you are able to "see" only a very few of the data points. If you had a data log, which records a larger number of readings per second, you could tell better what is actually happening.

Can you check the long term fuel corrections for left and right side at idle? The scanner should indicate that you are operating in Cell 16, and the long term corrections (aka BLM's) should be more than 108 or less than 160. If you have "pegged" the BLM at 160 (it can't go any higher, and it is still running lean, it is conceivable that the O2 sensor mV's for that side might still indicate a lean exhaust (~90mV).