Oxygen Sensor

[mark.wallace@mawallace1.d]

Had the yellow Engine Fault light on today. Dealer says it is a faulty oxygen sensor unit. Can anyone tell me what it does because the car drives the same as it has always done!

[european_bob]

Something to do with the emissions,im not 100% sure what it does.Im not a tech,but i do sell these bits and if ure avensis is anything before the new body is $$$$ £279.74 + vat.

Its a common fault if your model was built pre 2003(i fink),whenever the new body came out,the ugly one.

Used to sell loads of um,infact i fink every avensis must of had one now cos its been a while...

[sjrainsford]

Basically it tells your engine management what is going on in the exhaust gasses. This way it knows how things are going in the burn process, so it can use this information along with all the other sensors to alter the timing, fueling etc to get the engine to run at it's optimum.

The management will flag the CE lamp if there is a fault registered. It may report that the oxygen sensor is faulty, but this may actually be reading correct. The burn process may be way out due to a fault elsewhere. This has happened recently in another post by the looks of it.

A lot of faults are caused by other faults elsewhere.

However, the techy's will have diagnosed it correctly all being well. They should know what they are doing. Unfortunately, i'm not very trusting in that department.

[mark.wallace@mawallace1.d]

How many oxygen sensors is there on an Avenis? My managment light came on (again) today and Toyota dealer diagonised it as oxygen sensor. I pointed out that I had already had an oxygen sensor changed last month - the delaer says there is more than one!

[ulro]

Depending on how new your Avensis is, can be as many as three Oxygen sensors. The D4 2.0 and 2.4 L engines have three, two upstream and one downstream of the catalytic converter, other engines have one upstream and one downstream.