Well here is my delima. Recently my ses light pop up and it was the 02 sensors. Two of them. I shut off the light and that was that but am wondering can they still be bad. I reset the light and the SES light has not come back on. I know I am not getting good milage like I was anymore. Is there a way to check the 02's that I bought like three monthes ago. I got bosch. Can they have gotten bad? Well would like to here what everyone has to say about this so post up thanks.

 

Running leaded fuel and or lead in any additives introduced to the motor will reduce the life of an O2. A rich fuel mixture will shorten their life too.

An excerp I found for you.

Testing O2 sensors on the workbench.

Use a high impedence DC voltmeter as above. Clamp the sensor in
a vice, or use a plier or vice-grip to hold it. Clamp your
negative voltmeter lead to the case, and the positive to the
output wire. Use a propane torch set to high and the inner blue
flame tip to heat the fluted or perforated area of the sensor.
You should see a DC voltage of at least 0.6 within 20 seconds.
If not, most likely cause is open circuit internally or lead
fouling. If OK so far, remove from flame. You should see a
drop to under 0.1 volt within 4 seconds. If not likely silicone
fouled. If still OK, heat for two full minutes and watch for
drops in voltage. Sometimes, the internal connections will open
up under heat. This is the same a loose wire and is a failure.
If the sensor is OK at this point, and will switch from high to
low quickly as you move the flame, the sensor is good. Bear in
mind that good or bad is relative, with port fuel injection
needing faster information than carbureted systems.

ANY O2 sensor that will generate 0.9 volts or more when heated,
show 0.1 volts or less within one second of flame removal, AND
pass the two minute heat test is good regardless of age. When
replacing a sensor, don't miss the opportunity to use the test
above on the replacement. This will calibrate your evaluation
skills and save you money in the future. There is almost always
*no* benefit in replacing an oxygen sensor that will pass the
test in the first line of this paragraph.

 

thanks I will go buy a voltmeter tomorrow and test later this week.

 

OK, good luck and let us know if you found anything. If it is the oxy sensors at all. Could indicate a vacuum leak too.

 

Even though my ses does not turn back on does that mean that everything is ok though?

 

Not necessarily.

 

It does take quite a while to complete the drive cycle before emissions codes will come back up. They could be present, but won't display the SES light until the drive cycle has been completed. GM Drive Cycle will show you what needs to happen to get an "emissions system ready".

You might be hard pressed to read an O2 sensor with a voltmeter unless you make up a jumper/connector harness to plug inline for you to pull voltages from. One thing you don't want to do is puncture the wire jacket on the sensor. Kinda makes it hard to read the mV signal without puncturing the jacket. I have thought about this and this summer will make up such a harness to put inline with the O2 sensors and hook them up to an oscilliscope. I don't have a scope yet, but I will be buying one in the near future to make trouble shooting newer vehicles that much easier.