Engine light flashes five times every now and then

[DME]

The engine light has started to flash five times on my -05 RMK 900 and from what I've read it does indicate a problem with the exhaust temp sensor.

It's not flashing all the time, it comes on every now and then.
As soon as I let the revs down under 3000 rpm it stops flashing and I can then often ride for many miles before it startes flashing again.
It never flashes from startup, it always starts after I have ridden for a while and the engine is up to temperature.

I have not felt any changes in performance, it starts and idles as usual and pulls like a beast.
No overheating, no other problems.
The only change that was made to the sled prior to the problem was fitting a 4" riser block and extending the wiring to the handlebars. That was done by soldering and shrinkwrapping the joints. The sled was then ridden a full day over more then a hundred kilometers without problems, and the day after the light came on for the first time.

I've searched extensively and come up with some different possibilities:
- Bad exhaust sensor: seems most people have constant 5 flashes from startup til engine is turned off?

- Bad wiring: where does it usually go bad and wouldn't that also men that the light would come on from startup? Ar least sometimes? And would the light go out immediately at idle if the wiring was bad?

- Engine actually running too high exhaust temp (too lean) for some reason?



Thankful for any thoughts around this that can help me solve this puzzle


Cheers
Dan

 

[Newfusion900]

I had the exact same problem as you and it was the temp sensor. The check engine light would only come on after pulling hard for an extended period of time and then when you would let up on it and wait it would go out. I would try a different sensor

 

[DME]

Thanks Newfusion!

Is there any way to test the sensor other than replacing it?
Would be good to test another one without having to buy it...

Cheers
Dan

 

[Newfusion900]

They are hard to test because you have to heat them and measure the change in resistance. Check resistance and see if it is open.

 

[Jerseyrider]

As new fusion said the exhaust temp sensor is hard to check. The specs are
2.3mΩ @ 392f (200c) - 76Ω @ 1652f (900c)
And a quote from the manual: "This sensor is difficult to measure if temperature is below 392f (200c)"


What most of us do it check the resistance at cold and then use a heat gun to blow hot air on it. The resistance should go down. If not it's bad.

 

[DME]

Got hold of a used exhaust temp sensor for free and stuck it on.
Solved the problem right away

Thanks for the advice!

Cheers
Dan

 

[Newfusion900]

Man lucky you snagging one up for free. Those suckers can be expensive.

 

[DME]

Yes, you could say that again... The dealer over here wanted the equivalent of $367 for a new one
In the U.S. they seem to go for approx $120...

Generally, all Polaris-parts are three times the money over here. Makes it worth importing everything everytime if one has time to wait a couple of weeks for the parts !

 

[DME]

For future reference I checked the old sensor with the "multimeter and heatgun"-method.

When in room temperature there was no curcuit at all.

After putting the heatgun to it for about half a minute the sensor made a curcuit that started at 30 megaohms.

Continued heating it up and the resistance fell quite rapidly down to about 1,5 megaohms.

After that it suddenly started to go crazy, the multimeter started to show results that jumped all over the place.

Continued heating it and all of a sudden the resistance started to climb back up again, and didnt stop until it came all the way back up to 30 megaohms and then the circuit was broken once again.

No matter how long I heated it, it would not make a circuit again until it had cooled completely down.

After that the process could be repeated all over again with the same results.


Cheers
Dan