O2 Sensor Voltage

[Putter C]

Remember that the O2 sensor has no driving capability, so you cannot put an
resistive voltage devider on it. (As far as my knowledge reaches)

So I suggest an OP-amp with an "Infinite" input impedance (Voltage folower)
with the resistive devider after that.

Carlo Putter
Stellenbosch
South Africa



Date: Tue, 07 Sep 1999 22:12:46 -0500
From: Tom Sharpe <twsharpe at mtco.com>
Subject: O2 Sensor Voltage

Group, I made a 10 LED O2 display which worked fairly well but was hard
to read as I used assorted LEDs, etc. and it flashed a lot.  I built
another using an LCD display from a cheap meter (0-200 mv), a 9v power
supply (7809 chip etc.) and a 1/10 voltage divider (set of 1/4w
resistors). It works from a 12V power supply and a 1.5V battery -- reads
.1593 volts

It has 4 wires - sensor in, sensor ground, +12 and ground. I wired it to
my efi harness - replaced the LED display. I used a common ground (same
as the LED one). The meter displays 1 indicating the voltage is greater
than scale (> 2 volts).  My volt meter shows +14v (ok here) and .4-.7 v
on the O2 sensor (engine running).

What's wrong? I thought O2 sensors read 0-1V.  Is the meter too
sensitive? Am I getting feedback somewhere?  Do I need another ground?
HELP!!!   TIA.  Tom