02 Sensors

Man its been awhile....

anyways, need a quick reply, buying parts online for inspection time and Im gonna do the sensors. I heard that the one after Cat doesn't do anything but I was thinking what the hell they are all oem on a 94 sport. But I just left the wvu game and im a lil wasted so how many do I need. 2 right?

enjoy laughing at me. thanks


ps. i read this like 33 times and fixed all typos for ya

The pre-cat O2 sensor is used as a post-cat reference and for ignition control, the post-cat O2 sensor 'measures' exhaust O2 after the cat. The computer compares the two, and adjusts or lights up your dash when too far out of 'acceptable' range. Intended to supply computer and driver with status of cat (good/bad function).

If it's to meet emissions, try the one in the intake first. Thats the one that'll have effect on ignition.

If the cat's bad, well, replacing the post-cat sensor won't help...

I wouldn't say the downstream HEGO "don't do nothing" - more like, it shouldn't do anything if the cat is up to scratch. All it really does is verify catalytic converter function - not much else.

The upstream HEGO, on the other hand, is the one that reports a signal used for fuel metering feedback, and can cause trouble if it's not working.

Considering that that downstream HEGO, if orignal, is now something like 12 years old and subject to intense heat, it's probably half shot anyhow - and you'll probably want to replace it out of hand by now.

If you decide to get a "code reader" for your own inspections, you'll want an OBD-I compatible reader (since you're OBD-I, OBD-II didn't get started until 1996 or so. I'd consider having one a good idea.)

5-90

HEGO - Heated Exhaust Gas Oxygen (sensor.)

5-90

I noticed that they both have different part numbers, but is there any real differance between them?

eg: can a pre cat be fitted in place of the post cat and vice-versa ?
or do you need the 'correct' one in each place?

from looking at them the only differance i noticed was the length of the lead?
or am i missing something?