I've got an '04 DS and my oil light came on after a few hours riding. Turned out to be a oil return check valve. A spring had come loose and the check valve fell apart in the case. There are two valves. One behind the oil filter and another inside the case. Unfortunately, the dealer had to split the case on mine to fix it. Runs fine now but lost about 3 weeks riding time.

 

I have an 03 BAJA. I washed it with the hose gun and put it away.I took it out yesterday and noticed right away that the red light stayed on when I shifted into 1st.I thought,hmmm... I rode it around for several minutes and then turned it off.The fan didn't come on like usual.After another 2 min. ride to try to get the fan to come on, it finally did.
After reading this thread,I went out and check my sensors for water.Sure enough.There was water under the rubber seals and connections.I dried everything out the best I could and there was no change.I don't have a multi meter to test them.But I do have the shop manual!So any specs you might need, I have the 02-03 book.
This is the only thing in it about testing a sensor and it is the temperature sensor on the thermostat.

The multimeter should indicate an infinite resistance(O.L.),if not change the sensoer
If the resistance is (O.L.), heat the temp. sensor,above 239 degrees.The resistance should be 0.1 (then there is a horse-shoe in the bad-luck position), if not,replace.
Sadly there is only one reference to the oil sensor.It's talking about how to do a pressure test and one of the things to do is to remove it.Thats it.
Anyway,the quad is still a beast!!!!
I rode my friends quad around a little bit the other day.Wow what a difference.My DS is so awsome and it's stock.I love it!
Now I just have to get it fixed.
Brian

 

I did the same thing. I also power wash mine I like it clean. I installed an Auto Meter electric oil preasure gauge, don't get the machanical one. very easy to install. Just get your gauge go to a hardware store and get a elbo for the new oil sending unit that will come with the gauge(take your old sensor to match up threads I can't remember size off hand). I have a baja so I have a tach. I took out the oil and neutral light drilled a hole for the oil gauge spliced into power and ground from the tach and ran a wire to the new oil sending unit and bam its alive and works great haven't had a problem since I also drilled new holes and put the oil light whitch is just a water temp light know and neutral light back in it looks factory get alot of complaments. I will take a pic this weekend and send it to you.

 

i power wash mine alot and i've never had a crappy sensor yet,

 

I called my dealer yesterday and ther's a recall on 2004 ,he will put a protector on it ....

 

Can you elaborate on the protector? After you have yours changed, please let us know what the dealer did. I've had two sensors changed over the past eight weeks. No protector that I'm aware of.

Thanks!

 

Yeah, I think all of us '04 owners would be interested in that. I'll check with my dealer on it too.

 

In another thread a bulletin was communicated, bulletin: 2004-3. I believe the bulletin addresses the oil sensor boot. The new boot # is: 710 000 760.