O2 ?'s
 

1988 300-SEL
O2 senor -
What are indicators of O2 problems?
Do they need to be changed on regular basis - milege?
If so, are there other things that need changing at same time?
What?
Are there test that can be done to detect if O2 is bad or going bad?
What are the steps to changing one?

Thanks!

1988 300-sel
 

1.) "What are indicators of O2 problems?"... Bad gas mileage. (running rich)

2.) "Do they need to be changed on regular basis - milege?"... Not necessarily but yes. (although if it aint broke don't fix it)

3.) "If so, are there other things that need changing at same time? What?"... No.

4.) "Are there test that can be done to detect if O2 is bad or going bad?
What are the steps to changing one?"... Do you have a 'Scope' or a 'Multi-meter' that reads 'duty cycle' or just a 'Multi-meter'?

Steps to changing one - pull up passenger side carpet, unplug sensor. Loosen 2 tranny pan bolts, remove sensor wire from hold down clamp. Unthread sensor from downpipe. Reverse steps to install new sensor.

Not necessarily a wear item but O2 sensors do degrade somewhat over time. You may see a dramatic drop in fuel economy when one goes bad, but not if it is only slowly dying. A CO test can give some indication if: you can't get the CO numbers to hold, or if you see a delay in the adjustment of CO numbers in response to changes in throttle. The CO should numbers should adjust and stabilize pretty quickly when going from idle to 2K back to idle. Slow adjustment usually equals a dying sensor.