Hi All,

How many Oxygen Sensors does my truck have?

And what is the significance of buyer one With Advanced Evaporative Loss System (AELS) vs buying one Except Advanced Evaporative Loss System (AELS)?

Thanks for the help! I need to change my sensor soon so any advice would be appreciated!

 

Wow lots of typos there, but hopefully I can still get some help! LOL..

 

I'm assuming w a 99 you have AELS. Its two different sensors for two different systems. Or at least that's how I researched it. You should have 4 sensors total. Two on each side of the y pipe. You will have two before the catalytic converter (upstream) and two after (downstream). I don't remember if the up stream or down stream are different part numbers but they all install the same way.
I bought four of mine at autozone (Bosch) and they worked great.

 

4 O2 sensors. If you still have the decal under the bonnet check the Emissions Group.


How To Identify The Evaporative Emissions Family Of Your Discovery 1

 

Thanks Shift I sure do hope it's AELS because that one is cheaper LOL. Wow didn't know I had 4 until I started researching and saw upstream left or right and downstream left or right, etc., so I just wanted to confirm with all you Disco Gurus that I was understanding correctly..

 

Thanks OverRover! When you say "bonnet" do you mean "hood"?
And when I do find the decal will it say something about AELS on it?

Also, who is the Emissions Group?

 

OK, overlooked the link you posted, I will check it out, thanks!

 

Be sure you don't have any exhaust leaks at the manifold. These rigs are sensitive and can spoof you into thinking the O2 sensors are bad. They are probably bad if they haven't been replaced, but if you have exhaust leaks, get that taken care of first.

good luck