Truth about O2 sensors...

[Hawkster]

Originally Posted by jekaio

the PCM sends no signal to the O2 sensors.

o2 sensors generate their own voltage.

either O2 sensor can be heated, upstrem or downstream.

the heaters on heated o2 sensors run when the car is below 3000rpm.

When a non-heated O2 sensor is below 600F it will run on preset parameters.

That is partially correct. SOME 02 sensors create their own voltage. Many of them (especially in newer cars) have a 1v reference signal sent to them by the PCM. The sensor then modifies the signal depending on oxygen content in the exhaust, and sends the new signal back to the PCM. As far as heated, yes, Upstream and Downstream 02's can be heated, but our cars in particular have just the Upstream sensor heated.

[Hawkster]

Originally Posted by Bill Strong

Hawkster - do you have an ETA?
I am getting ready to build a new manifold back exhaust system. I want to use a resonator in place of the cat. But if I need to I will just flange a high flow 3-way cat and install that.

I'm thinking about 2-3 weeks...

[bimmerboi318]

All O2S generate voltage. Most newer cars use a bias-voltage of 1, 2.5,
or 5 volts. Most newer cars (when I say newer I mean pretty much anything OBD2) use a pulse width modulated heater, more or less a variable strength heater, to keep the sensor warm as required.

That was a great description of how the sensor works Hawkster. How is it at UTI?

[Hawkster]

Originally Posted by bimmerboi318

That was a great description of how the sensor works Hawkster. How is it at UTI?

As you can tell by my description of O2 sensors... I have picked up some information at the school... BUT... in my opinion it was not worth the $23,000 tuition for a one year program. The school has a tendency to sell you the American Dream before you get there.... telling you you'll be making X amount of money, and you'll come out of the school having A-tech knowledge. Yea... so once you actually get into the classes... the school 'revises' their statement... and tells you that you will gain only a basic education... and that you'll be starting off in the field as a oil changer, making $10 - $12 an hour.

I'm sorry... but had I known I was going to learn as little as I have so far at UTI... I wouldn't have left my $60k/yr parts manager job. What I had WAS the American Dream... 20 year old college drop out (19 yrs old at the time) making $60k+ a year.... Oh well... live and learn... right?

[JPerfect]

I figured i would post on this thread because i'm having a problem with my o2 sensor. i have an M42, and I keep failing for emissions. no CEL, no error codes... just high hydrocarbons. so i changed the plugs, and figured I'd pass since I failed by like 20 (very small margin). I also had noticed that i was experiencing low gas mileage, and the car felt lethargic accelerating in first gear.

So today, since it's about 57 and sunny (about 30 degrees above normal) i'm outside as we speak. i disconnected the o2 sensor, and decided to start my engine. i was surprised to still see no error codes or CEL... Is there an amount of time I have to wait for it to reset, or do I need to disconnect my battery? i'd hate to have to buy another O2 sensor if i don't need it, but i'm willing to do anything at this point, as I have to pass inspection by next monday.

thanks, Jeff

[DustenT]

Originally Posted by JPerfect

I figured i would post on this thread because i'm having a problem with my o2 sensor. i have an M42, and I keep failing for emissions. no CEL, no error codes... just high hydrocarbons. so i changed the plugs, and figured I'd pass since I failed by like 20 (very small margin). I also had noticed that i was experiencing low gas mileage, and the car felt lethargic accelerating in first gear.

So today, since it's about 57 and sunny (about 30 degrees above normal) i'm outside as we speak. i disconnected the o2 sensor, and decided to start my engine. i was surprised to still see no error codes or CEL... Is there an amount of time I have to wait for it to reset, or do I need to disconnect my battery? i'd hate to have to buy another O2 sensor if i don't need it, but i'm willing to do anything at this point, as I have to pass inspection by next monday.

thanks, Jeff

Does you CEL come on when you turn the key to the ON positions? All of the dummy lights should light up, then go off. If you CEL light doesn't turn on at all, then either the bulb is burned out or someone removed the bulb.

[JPerfect]

the cel come on when i turn on the ignition, and when i check for error codes. it also came on when i pulled the mAF. the car sure sounds crazy when that O2 sensor isn't plugging that hole in the exhaust...

[JPerfect]

bump!!~