Re[2]: Advice on installation of O2 sensor on 73 115?

[James Montebello <jamesm@domain.elided>]

On Wed, 26 Feb 2003, Richard Welty wrote:
> the extra pair of wires in a 3 wire O2 sensor is for the heater. O2 sensors
> need to be hot to do their job, and the heater is simply there to allow the
> O2 sensor to start working sooner when an engine is warming up.

It also makes sensor positioning much less critical.  An unheated sensor
all the way past a 4-2-1 header probably will never get hot enough to
read accurately.  Even if it does, the inconsistent temperatures as
you run at cruise and WOT for testing will skew the results enough that
using the sensor will be a waste of time.  You could probably do as well
with plug chops.

The price difference is small ($20), and the extra wiring is not that
big a deal.  Spring for the heated sensor.

james montebello
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