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· Premium Member
14,078 Posts
Discussion Starter · #1 ·
I think its time to sell my truck... 1997 Chevy S10 with 4.3 V6...

I know the O2 sensor is bad, keeps throwing codes every week or so (and two dealer visits mentioned the O2 sensor, but not which one). Today, the Check Engine light was off...

I was told there were 2 sensors (upstream/downstream), but searching for prices, looks like maybe 4 sensors (2 each bank????)...

Is there an easy way to test these to see which ones are faulty? Cheapest I have found is $50 each...

I am ready to just pay $5 for just enough gas to torch the whole truck!!!

· Premium Member
1,227 Posts

You can check with either a scanner or a decent
multimeter. Normally OB11 vehicles have a sensor
both in front and behind each converter. The rears
only monitor converter efficiency. Some cars have 2 front sensors then to a Y pipe where there is only 1 converter. In this case you'll have 1 front sensor for each bank. 1 sensor just before and just after the converter. On the fronts or anything upstream (before the conveter) you should see voltage switching fairly quickly
between approx .2-.8 volts. The signal return wire
is purple or tan. I can't remember which for sure
so try it both ways. If the voltage is changing really slow or it fixed at about .5 volts then thats likely the sensors that are failing. On the rears the voltage should be steady around .7 volts or so once the car is warm. You should be able to check the heater circuits by ohming between pink an black wires. You'll see some resistance if elemnent is not open.. Hope this makes sense..
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