oxygen sensor

[peter smith]

how do you check the operation of a oxygen sensor if you dont have $100000 machine to play with

[Not_An_Abba_Fan]

You will need a multimeter. A digital one is better, set it read o.oo volts dc. Connect the positive to the signal wire and the negative to an earth. You will need the engine and O2 sensor to be warm. Take it for a drive first. Then after connecting the multimeter, rev the engine to 2000 rpm.

Observe the reading on your multimeter, it should go up and down between 0.2 and 0.7 v rapidly, if it sits around 0.45v it isn't warm enough, or it is buggered. Rev the car a couple of times to 3000rpm and see what happens. If the volts don't change your sensor needs replacing.

If it fluctuates, the next step is to test whether it is reading correctly under lean/rich conditions. Remove a vacuum line and see if the volts drop down to around 0.2, if it does it is good. To see if it reads correctly rich, you will need to introduce extra fuel. this can be done by dipping the removed vacuum line into a container with some petrol in it. The volts should go up to 0.7.

Sometimes the sensor can be carboned up and not read correctly. You can clean it on the car by unplugging it, revving the car to 2000rpm to get it warm, then remove a vacuum line to create a lean condition for 1-2 minutes while at 2000rpm. If the sensor still doesn't respond after doing this, replace it.


Note: the sensor needs to be connected to perform this test, you will need to probe the wire or create a bridge at the plug.

[peter smith]

Many thanks for answering my question,i will try it on the week end and let you know how i got on
regards peter smith

[peter smith]

Thanks for the info, the Oxy sensor seems to be within specs. the fuel comsumption is between 9.5 to 11.5 lts/100km depending on how it is driven.
As the engine wears and manifold vacuum drops this will have a affect on the MAP sensor (ie the engine will run a bit richer ) Do you know if there is a way of adjusting the sensor to compensate for general engine wear.
Kindest Regards
Peter Smith