Test Oxygen Sensor?
 

Hello,

Ocasionally the check engine light illuminates on my 94 e320 sedan. When it comes on, I usually get five blinks from the diagnostic led. I've been told that this means the the O2 sensor is not working. If I clear the code, the light will stay off for a month or two before it comes back on again.

Is this a sign that the O2 sensor is dying, or is it the work of electrical goblins? The wiring harness and computer have never been changed in this car.

Is there any way to test the 02 sensor before I go out and buy a new one?

If it is in fact failing, what damage is it doing to the car by not changing it immediately.

Thanks,
Will

Code 5 is EGR circuit.
Check the archives for the egr valve tubing blockage at the intake. Common problem on 104 eng.

Apply vac to egr at idle . Should make eng run rough. If not, suspect egr valve/blockage.
02 sens is code #2.

Thanks for the help.

Your Welcome.

If you still have a problem after doing the test and cleaning, be aware that there is a part change of the egr on your model.
If that info is needed, you may email me direct for it.