How To Test Oxygen Sensors Are Good ?

[COFFEE]

High all,
Is anyone able to assist me ?
Is there a way of testing the oxygen sensors are working properly ?
If so what is the procedure and figures ?

Regards

Stephen

 

[Peewee]

Its something along the line off
- Get the car up to full temp
- Hold the throttle around 2500rpm
- unplug the connector - test voltage to ground.
- should be ocsillating between 0.3 and 0.5 volts about 8 times per 10 seconds.

Don't quote me, but its soemthing like that.
I'm not sure if you can do it straight from the diagnostics box, which would be much quicker than unplugging them.
Would be O1 and O2 in the box.

 

[MWP]

That wont work...

If you unplug it, the ECU will run in open-loop or limp-home mode and not lean out meaning you wont see that oscillation anyway even if the EGO is ok.

 

[Peewee]

Ok then, use the diagnostics connection.

 

[sideshow]

one of the terminals on the oxy sensor shouold have 12v when runnin this is heater

one terminal should ahve around 1 volt this is the signal wire

check this voltage as u rev the car voltage sgould change very slightly up or down as u rev and back off

then u can check the same wire at the ecu

to see if the voltages are same incase u have break in wire

 

[edz]

The way I checked some old ones was with an oxy and an ohmeter, the resistance will vary as you heat them up (but don't burn them!).

The only problem is, an oxy sensor can appear to work, give fluctuating voltage or resistance with all the above tests, and still be crook - giving innacurate readings to the ecu (they should generate a fault code). An engine analyser is the only true way to check it with a 4 wire oxy sensor up the exhaust for comparison and the diagnostics plugged in. If they are crook, replace them.