964 o2 sensor life expectancy

[cnavarro]

Question. How long does an o2 sensor last? I've had newer non-porsches go through sensors like oil changes (every 3k). My 91 has roughly 47k original miles on what I would presume is the original sensor. I just ordered a Steve W chip and want to make sure that it is still in good enough shape to be optimal with the new programming. That said, there's only one sensor on a 91, right? I'm used to cars with four sensors.

[Steve W]

Charles, as a rule of thumb heated sensors such as on the 964 generally last around 60,000 miles, unheated around 30,000. Sensors don't usually suddenly fail, but go through a phase of reduced sensitivity and slower reaction time, until they finally give up. Sensors should last way longer than 3k miles, unless contaminated by leaded fuel, silicone, or excessive heat such as from being placed in too close a proximity of a turbocharger. The 964 only has one sensor.

O2 sensors are not really required for proper engine operation, however they are needed to maintain a stoichiometric air fuel ratio of 14.7:1 at idle and steady state part throttle conditions (where we are 80-90% of the time) to keep the cat happy and emissions lowest. It also helps to keep the idle and part throttle mixture more in line when there are out of tune conditions (i.e. vacuum leaks, clogged injectors, out of tolerance sensors etc) although it should not be used as a crutch for a poor maintenance.

[cnavarro]

My first car was a ford and it was at the dealership every other week basically until it crapped out at 60,000mi. It ate injectors, ecu's, o2 sensors (had four) and many, many other things. Good thing for extended warranties!

I'm looking forward to the chip Steve! I might just change the o2 sensor at the same time since i'm close enough to it's full life and they are not that expensive.

[Rouxzy]

Charles,
I received my chip from Steve last week and you are going to love the differance. My engine now idles perfectly and runs much smoother. Oh yeah, the added power is very noticeable.
Tom

[Steve W]

Tom - glad to hear and thanks for the feedback! Charles, I think you'll also like the new extra grunt - however let us know how it goes.