O2 sensor replacement

[JGriff]

Looking through all the receipts on my recently-acquired 1990 944 S2, I did not see a receipt showing the O2 sensor being replaced. (I am planning on contacting the PO just to make sure.)

My car now has 75k miles on it. What is the change interval on these cars? Usually for most cars, it is 60k miles.

Should I change it now, just to be safe, and to make sure that the car is running properly? (Usually, O2 sensors degrade slowly over time, and the performance loss is usually not drastically noticeable... is degrades slowly as well. I want to make sure that the car is at peak performance.)

How easy is this to do? Is there a post here somewhere (I did a search, and found a lot of discussion about cold air intakes, lean/rich problems, but nothing about replacement), or a web page with pictures and procedures on how to replace one on an S2?

I've replaced the O2 sensors on my Audi... so I'm not afraid to do it myself... I just need some general BTDT advice etc., since I do not have a repair manual for this car yet.

Thanks in advance.

Happy New Year!!

Jim

[Scott R]

They seem to last forever on these, just check it to make sure it works. Unplug the connector on the rear of the intake manifold, if you notice a raise or decrease in RPM's it's working. My 951 has no record of ever having it's replaced and it's at 81k.

[arnebret]

While we're at this topic... i'm pretty new on the O2-sensor on the 951, i get the complete system, but how is the system wired in the 951. The O2-sensor is placed in the exhaust, it measures the O2-level and is sending info through a wire, to...? Where does the info come in and what kind of processor is doing changes on the mix as the O2 level raises/drops?

[Scott R]

It's an impedance signal sent to the the DME which in turn adjusts the amount of fuel/air/ignition according to the signal, which helps the computer react to changing driving conditions.

[TomH]

I just ordered a universal from Paragon for $38. I pulled mine last week to inspect, and the white residue resembles spark plugs that are running lean. I'm replacing mine to see if it improves my mixture. (my plugs also show signs of running lean).

FYI: NAPA sells the same Bosche universal sensor for $95!