How to Check the oxygen sensor (High fuel consumption)

Max · Post by **Max** » Sun Jul 23, 2006 2:34 am

Today I unpluged the wire (the pink color wire ) of oxygen sensor , then start my car . Everything is ok , and the "engine check" indicator is off

Then I check the resistance between the wire of oxygen senor and car body. Found it is infinity or disconnected.

Finally I check the outside of oxygen sensor and the car body, only few resistance.

Is my senor broken ? Seems our sensor is very old type , only have one signal wire to ECU.

Daniel · Post by **Daniel** » Sun Jul 23, 2006 7:01 am

You can't check this oxygen sensor by checking it's electrical resistance. Read http://en.wikipedia.org/wiki/Exhaust_gas_oxygen and here http://www.picotech.com/auto/lambda_sensor.html how it works .
The best way to check this kind of sensor is to connect it in derivation to a oscilloscope while engine is running and looking at the waveform. For a good sensor you should see quick voltage changes between approx 0.2volt and approx 0.8volt.
A bad sensor will throw a "engine check" while engine is hot and running in "closed loop".

Daniel

asam · Post by **asam** » Sun Jul 23, 2006 9:03 am

You can replace it with a new bosch oxygen sensor but I doubt that your sensor is the problem. There are tons of things that could affect the gas milage.

Max · Post by **Max** » Sun Jul 23, 2006 9:07 am

asam wrote:You can replace it with a new bosch oxygen sensor but I doubt that your sensor is the problem. There are tons of things that could affect the gas milage.

What is the model or code of bosch oxygen sensor ? How much will it cost ?

asam · Post by **asam** » Sun Jul 23, 2006 9:13 am

Ok, I'm not quiet sure, but waults (in the US) can find a match. I think it costs $40. They will charge you like $80 for everything installed. But if you have the tool, do it yourself.

Ok i heard this from some mechanics, so do this at your own risk. I heard you could clean the O2 sensor by heating it with a torch. It melts off the carbon deposits and other irregularities. I'm not that brave. You could try some brake cleaner....I use it to clean spark plugs and it works fine. Just make sure you let it dry out before reinstalling it.