Without wishing to sound thick (I'm no electrician or physicist)...

I've just bought a cheap multi-meter and when I go to test the sensor, to get a reading, am I supposed to...


...unscrew and withdaw the sensor's head from the exhaust manifold...

...run the engine up to temp...

...with engine still running, touch the red positive probe onto the end of the sensor head...

...whilst touching the black negative probe to earth on a bare metal area of the car chassis , to create a circuit?


Am I barking up the right tree, anyone?


(BTW I know what voltages to look for, for a correctly functioning sensor)

Thanks, John

 

C'mon... surely there's someone out there that's done this and can let me know?!...

 

bttt... (?!)

 

You need the sensor in the exhaust to get a reading....
What year of car is it as this has an effect on which sensor is being used and which wires need to be probed...

 

As MartynJ said, leave the sensor in the exhaust.
The oxygen sensor will have a three pin plug with one pin colored gold while the others are colored silver. You will need to measure the voltage between the gold pin and ground (the car body).
My preferred method was to get the connection off the ECU socket but you can get it by splicing into the wire at the plug and run the wire into the car..

I think to get a proper diagnosis on an O2 sensor you would need to monitor it from startup to notice how long it takes to warmup and afterwards watch its response during cruising and on boost.

 

Thanks for the replies.

I told you I was no physicist - of course the sensor needs to be in the exhaust, doh!

However, it seems to be a bit more in depth than I originally thought, and looks like there needs to be two people - one to drive, one to test?

When warming up, should the voltage remain stable at anything between, say, 0.3V-0.6V, but once warmed up, should it cycle between 0.1V and 0.9V, about once every second?

 

When warming up, which should be within 5 minutes for a properly working sensor, the maximum voltage you see should rise from 0 to at least 0.7v. And from there it should oscillate above and below 0.5v about once every few seconds (like 3)

 

Cheers saiklon, I understand

 

loads of info on here m8!
Just Lambda NTK, Suppliers of NTK lambda sensors by post..