I have seen a couple of threads on this.

What is the best way to check O2 sensors of the car,

I can heat up with a blow torch. And have a multimeter

But which wires should i connect it to.??

And what voltage range should show a decent sensor.

Ive got 6 to check, and all are showing voltage.

Either im doing it wrong or they are all shagged.

Help please

is this any help ?

 

Testing O2 sensors on the workbench.

 

Use a high impedence DC voltmeter as above. Clamp the sensor in a vice, or use a plier or vice-grip to hold it. Clamp your negative voltmeter lead to the case, and the positive to the output wire. Use a propane torch set to high and the inner blue flame tip to heat the fluted or perforated area of the sensor. You should see a DC voltage of at least 0.6 within 20 seconds. If not, most likely cause is open circuit internally or lead fouling. If OK so far, remove from flame. You should see a drop to under 0.1 volt within 4 seconds. If not likely silicone fouled. If still OK, heat for two full minutes and watch for drops in voltage. Sometimes, the internal connections will open up under heat. This is the same a loose wire and is a failure. If the sensor is OK at this point, and will switch from high to low quickly as you move the flame, the sensor is good. Bear in mind that good or bad is relative, with port fuel injection needing faster information than carbureted systems. ANY O2 sensor that will generate 0.9 volts or more when heated, show 0.1 volts or less within one second of flame removal, AND pass the two minute heat test is good regardless of age. When replacing a sensor, don't miss the opportunity to use the test above on the replacement. This will calibrate your evaluation skills and save you money in the future. There is almost always *no* benefit in replacing an oxygen sensor that will pass the test in the first line of this paragraph.

 

Maz :)

....and the stock engine built in diagnostic method is no good? Worked fine for me and exposed a bad connection on the connector blocks.

....and the stock engine built in diagnostic method is no good? Worked fine for me and exposed a bad connection on the connector blocks.

 

Agreed! Stick it in mode 2 diagnostic mode with the sensors installed & check the O2 sensors are switching.

 

I have never tried testing by heating them up to be honest but not sure what this would test - yes, the sensor has to be up to operating temperature to work but switches depending on the oxygen content (how rich or lean the mixture is) not how hot the probe is?!

 

If it switches just because the temperature is in the operating range & when it cools down, how do you know if it is switching based on mixture??

Thanks for your help guys, i tried the Maz way, put into a vice and neg tothe body of the sensor, and red wire to connector.

When totally cold, shows a tiny amount of volts (probably from multimeter)

but on heating the end with blow torch, volts shot up very quickly to .9

remove heat and within about 1 sec, drop dramatically to below.1

on doing the 2 min test, it shows ranges all over .

This would say i have some decent O2 sensors.

Bargain now, as i bought 2 spares from a member, and 2 came with my new zorsts, plus two good ones on my breaker

Total of 6 good sensors.

Did the same test on the dead ones of the Uk and didnt show any reading at all.

 

Cheers. Its nice to have help returned.

Agreed! Stick it in mode 2 diagnostic mode with the sensors installed & check the O2 sensors are switching.

 

I have never tried testing by heating them up to be honest but not sure what this would test - yes, the sensor has to be up to operating temperature to work but switches depending on the oxygen content (how rich or lean the mixture is) not how hot the probe is?!

 

If it switches just because the temperature is in the operating range & when it cools down, how do you know if it is switching based on mixture??

 

 

At a guess i would imagine that it switches when the heat is on it because the flame of the torch is starving the sensor of oxygen and not down to being hot and cold??? Just a guess really, but i can see how the test would work though if this is the case. :)

Pages 48,49 and 53 discusses the mode 2 diagnostics procedure ... with such gems as

 

"HOW TO CHANGE MONITOR FROM LEFT SIDE (Right side) TO RIGHT SIDE (Left side)"- what is that supposed to mean? :no:

 

http://www.300zx.co.uk/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&slide=48&cycle=off&scale=0&design=default&total=190

 

HOW TO CHANGE MONITOR FROM LEFT SIDE (Right side) TO RIGHT SIDE (Left side)

 

Doing this meself today

Pages 48,49 and 53 discusses the mode 2 diagnostics procedure ... with such gems as

 

"HOW TO CHANGE MONITOR FROM LEFT SIDE (Right side) TO RIGHT SIDE (Left side)"- what is that supposed to mean? :no:

 

http://www.300zx.co.uk/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&slide=48&cycle=off&scale=0&design=default&total=190

 

HOW TO CHANGE MONITOR FROM LEFT SIDE (Right side) TO RIGHT SIDE (Left side)

 

Doing this meself today

 

It switches between the 2 banks - left O2 sensor test then change to right O2 sensor test to see each sensor in turn switching

Aye I can appreciate that, but why does it say "LEFT SIDE (Right side)" and "RIGHT SIDE (Left side)"?

 

Both pieces of advice are literally absolutely ambiguous, unless I'm missing something mechanic-specific terminology to disambiguate it e.g. 'capital R in Right = near-side'?