So I was doing a service today and decided to do a diagnostics check and pulled a code 41 which relates to the air temp sensor. First thing I checked was the wiring as I've read that some times a wire will pull out of the plug or wear a bare spot from chaffing against the frame or what-not. Everything looks good including the plugs themselves. I always use dialectic grease on everything possible and the plug looks great. I've noticed no change in the bike other than it idled funny for just a couple seconds and then smoothed out. That may just be because it's colder outside now. I never paid much attention to cold starts before with this bike. I would have never known there was an issue if I hadn't done the diagnostic.
1.So my question is how can I test the air temp sensor?
2.How vital is this thing?
3.With this on the fritz will it cause me to have a lean or rich condition and how bad?

 

The air temp sensor is used to help control the air/fuel ratio, if its bad it could cause a rich or lean condition depending on how the sensor is acting. Did you pull the sensor out and clean it, sometimes it can get dirty and not read properly.

 

It did have a medium film of dust on it but nothing to extreme. I'll try pulling it and cleaning it thoroughly. Does anyone know how to clear codes so I can verify if the problem is fixed? Disconnecting the battery???

 

Disconnecting positive lead for about 20 seconds should clear the codes..

John

 

I cleaned the sensor and still pull a code 41. And it still stutters for a few seconds on a cold start. Is there a test I can perform with my fluke/ohm meter to check it?

 

Sounds like you need the t bap wire harness repair kit...On mine the wires weren't visibly broken but sometimes they fail inside the plug...If I were you I would visibly check the 4 wires for breakage first...They are very thin wires and are very suceptible to breakage due to the vibration....

John

 

I'm puzzled now! Apparently the 500's are slightly different from the 700-800's. The air temp sensor on my 500 is in the air box unlike the 700-800's and I can't locate a T-bap on any schematic for it? There isn't one where you would traditionally find one on the twins. Do the 500's even have a T-bap??????? I would think so but be danged if I know where it is. Or does the air temp sensor in my air box act like the T-bap would on the 800's.

 

Never mind my last post. I found the steps to test the sensor with an ohm meter in my service manual. I guess I need to read the book not just look at the perty pictures. GARSH! LOL. And for some reason the 500's don't have the dreaded T-bap's. So no worries there.

 

My 500 EFI always runs a little rough when it's cold.

And I really think nothing of it. Afterall, it's and ATV and single cylinder! LOL!

What I do wonder about is why it takes so long for the cooling fan to kick-on while working hard plowing snow. My engine seems to get very hot before it finally kicks-on.

 

Mine is running noticeably rough for 3-4 seconds then smooths out. Not normal in my opinion. But if my sensor is out that would explain it. As far as your fan kicking in I don't know? Mine never has a problem getting really hot before the fan engages. Sometimes I think it kicks on a little to often.