Oxygen Sensors

Maintenance/Repairs
1

Is it true that downstream oxygen sensors does nothing but monitor the catalytic converter & doesn’t affect engine performance such as a rich or lean condition ? The upstream sensors monitor rich or lean conditions , correct ?
Has anyone ever used a handheld oxygen sensor tester and or tested the sensors with the propane torch method ? There are u tube videos of both being done .

2

@Sloepoke

“Is it true that downstream oxygen sensors does nothing but monitor the catalytic converter . . .”

True

“The upstream sensors monitor rich or lean conditions . . .”

Correct

I haven’t tested sensors with a propane torch

That would be testing for response to a rich condition

But I’ve done the opposite . . . create a huge vacuum leak, to see how fast they respond to a lean condition

I’ve never heard of the “handheld oxygen sensor tester” . . .

3

If you check ebay or amazon for ST 105 oxygen sensor tester you’ll see what they are . There’s also a u tube video of one being used . I’m sure there’s probably other brands also . If it works as advertised it would be a handy thing to have . I’m considering buying one but wanted some input first . They’re about $105.00 .
Could anyone recommend a reasonably good code reader that’s not real expensive ?

4

Don’t know where I got the 1 at in that number . Just checked & seems like it’s an ST 05 but it comes up either way .

5

Actually it’s a GTC ST05 . Is there a way to edit posts ?

6

@Sloepoke

Thanks . . . I’ll check it out

As far as editing . . . move your cursor to the far right, next to your post. A gear wheel will appear.
Click on it and the edit button will appear.

7

For a good, cheap code reader try an Actron CP9575. I paid $80 about a year ago and it works great. There may be a newer model now but I have used this small scanner to pull codes, reset CEL’s, and run real time readings of O2 sensors.

8

Is it true that downstream oxygen sensors does nothing but monitor the catalytic converter & doesn’t affect engine performance such as a rich or lean condition ?

No that is not true. That may have been the case once but that information and theory is outdated. Chrysler products have been using both upstream and downstream oxygen sensors to control fuel trim for at least 10 years now. Other cars may do the same.