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Checking oxygen sensor on Corolla


davelew's Avatar
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01-05-04, 09:35 PM   #1  
Checking oxygen sensor on Corolla

I have an 86 Corolla LE with 4AC engine. Tested the oxygen sensor via the service connector. The voltage swings between 0-4.2 v about once every second at 2500 rpm. Manual say it should swing between 0-7volts. Does the low voltage reading (4.2v) indicate a bad sensor?

Also, did they make the earlier oxygen sensors put out higher voltages? Seems like what I've read about most oxygen sensors, voltage readings are under 1 volt.

 
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01-06-04, 04:01 AM   #2  
That's correct. O/2's rarely peak over 1 volt. They generally jump between .100 and .900. If you are getting a reading over 1 volt, then your are either on the wrong wire or there is a problem. If it has more than 2 wires, it has a 12 volt heater and could be bleeding over although I don't remember an older Toyota having a heater.

 
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01-06-04, 06:09 AM   #3  
The reading you are getting is correct. It is reading the 0-7 volts from a Feedback computer. At the sensor it would be 0-1.0 volt like Desi stated.

So therfore you sensor is reading lean. Hold you hand slightly over the top of the carb to richen and see if the sensor will respond by outputting a higher voltage. If not the sensor is NG.

 
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01-08-04, 12:58 AM   #4  
I repeated the test on the oxygen sensor with my hand held slightly over the carb and voltage did not go any higher. I'll be replacing that sensor with a new one.

Thanks for the replies.

 
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01-09-04, 11:13 AM   #5  
port649
What is the problem with the vehicle? The O2 sounds ok, you may be replacing a good O2!

 
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