O2 sensor test help ?

[magnoman]

I have a 98 225 EFI , I have been cleaning the 02 sensor and the small rod that goes in to the exhuast chamber on a regular basis. I just took it off the other day to check and see if there was any carbon build up and it was fine. reinstalled the sensor and know at low rpm she shakes and runs rough around 800-1400rpm. never did that before? I noticed that the wires on the top of the 02 sensor the wires look to be pinched and not in good shape from removing it so many times. Is there and way to check ohms or continuity to see if the wires are broken? before I go and buya $300 part?

 

[tommays]

Re: O2 sensor test help ?

Wag here

But there is some kinda of test plug that you use and with the motor running and watch the output on DMV to see if it matches the spec in the service manual



Tommays

 

[vx225mota]

Re: O2 sensor test help ?

You can get buy without the test harness.

Just push your multimeter probes into the back of the connector that the o2 sensor plugs in.

You should get a voltage reading.

It should range between 0.1 volts and 1.0 volts depending on o2 readings. Search here for more info if you want to know what it means. But at least you know it will be working.

Either way, it is a simple two wire thing, you can cut and join the wires, fix connectors or whatever. Just make sure you maintain the same wire going to the same wire

 

[magnoman]

Re: O2 sensor test help ?

Thanks for the info , but mine has four wires coming out splitting to two connetors? one connector has a Blk & Gry wires the other connector has two white wires going to it? witch one do I test for voltage?
The wires are kind of pinched right at the base where they go into the o2 sensor it would be really hard to fix?

 

[JUSTINTIME]

Re: O2 sensor test help ?

there is a tech bulletin
go to the dealer and ask for the bulletin and buy the test harness

 

[vx225mota]

Re: O2 sensor test help ?

You can safely test either pair. One is for the o2 sensor heater which is used to heat the sensor at low RPM or when first started. The other is for the output. I'm pretty sure it is the black/grey but you will soon see.

One will have 0.1 to 1 volt the other will have about 12 volts.

 

[reeldutch]

Re: O2 sensor test help ?

are you shure the o2 sensor is causing this problem.
the o2 sensor is the last sensor the ECU will use to compensate the motors actuators.

 

[rodbolt]

Re: O2 sensor test help ?

O2 sensor input is used for fine tuning the fuel mix by the ECU. the 2 white wires are heating element wires and should have 12V or better with key on, the gray and black are output to the ECU, at operating temperature with the lower unit sumbmerged it should scale between .3V and about .6. anything else indicates a problem. there are actually 3 ( at least) tech bullitens on how to test the O2 sensor output.without the sensor fuel is fixed rich at idle and lean above 4000 RPM. if you suspect its not working DO NOT run it above 4000.
have you checked the plug caps and the fuel pump diaphrams?