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Discussion Starter · #1 ·
The dealer replaced the speed sensor on my 1 year old Ace yesterday. For a while I have been experiencing the symptoms that have been described on the forum of an intermittent check engine light when driving slowly. It happened almost every time that I was rock climbing.The part was $59 and the entire thing was covered under extended warranty. The dealer charged 1 hour of labor to replace the speed sensor.
 

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I have had some issues with the check engine light coming on when using low, but it resets itself. I read someplace its to sensitive? Code 84 if I remember right.
 

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Discussion Starter · #3 ·
I wanted to let the forum know that the new speed sensor did not help at all. I drove the Ace on a slow trail this afternoon and the check engine light came on after about a minute of slow driving. I have contacted the dealer and they are checking with Polaris to see if there is an alternate solution. I hate that the extended warranty people paid for something that did not help. I should hear back from the dealer by noon tomorrow.
 

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Discussion Starter · #5 ·
I talked to the dealer today. They heard back from Polaris and there is no fix for defective Ace speed sensors. The speed sensor on the Ace is the same part as is used on several other models, including the RZR 900 according to service manager at the dealer. The dealer said to bring the Ace back in and they will replace the speed sensor while I wait. He said that he suspects that there may have been some manufacturing problems as they have been replacing a lot of speed sensors. I will take the Ace in next week and get yet another speed sensor.

I have one trail that is about 3 or 4 hundred yards long that is in the bottom of a narrow gulley. The trail is very rocky and uneven and I am on three wheels most of the time. I have to ride the trail in low range and barely crawling. Every time I ride this trail I get a check engine light. They are relaying this information back to Polaris. This trail is so uneven and narrow that my friend Greybeard tore up the top on his RZR 900 XC banging into trees. When he tried to avoid the trees he got too high on one bank and rolled his RZR. He has ridden the trail many times on his Ace with no problems.

I did find out where the connector is that the dealer plugs the computer into to read the diagnostic codes. I rode the yellow jacket trail again today and got a check engine light again. I looked down and a cable with a large connector was dangling beneath the steering wheel. When I got back to the house I found the park position for the cable near the steering column. The dealer evidently did not properly park the cable after he disconnected his computer.
 

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Hope the new new speed sensor clears it up for you.
Could your issue be belt slip, rather than a faulty speed sensor?
Do you have spare belt on hand? This might be a good time to buy a new belt, put the new one in, and stow the old one as a spare, and see if that corrects the CEL problem in that rough spot.
 

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Discussion Starter · #7 ·
Scoundrel, I don't really know the answer to your question. Can a belt slip turn on the check engine light? I have been thinking about a spare belt for a while. The dealer says that the stored code is from the speed sensor. If the new speed sensor that I get next week does not solve the problem then I will replace the drive belt.
 

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I thought I remembered something about a belt slip causing the speed sensor to go on, but looking back at the previous speed sensor thread, I think now that I must have been smoking too much crack that day.
So disregard the belt thing - although carrying a spare is never a bad idea.
Here is the other speed sensor thread, wherein you might find some useful information: http://www.aceforums.net/forum/9-ace-talk/266-diagnostic-codes.html

Here is something I found over on Polaris ATV Forums that may help understand a little better what is going on:
Crankshaft Position Sensor (CPS) – Located on the aft side of the stator cover. Also known as the engine speed sensor, the CPS is essential to engine operation, constantly monitoring the rotational speed (RPM) of the crankshaft. A magnetic, 60-tooth ring gear with two consecutive teeth missing is mounted on the flywheel with the inductive speed sensor (Hall Effect sensor) mounted immediately next to it. During rotation, an AC pulse is created within the sensor for each passing tooth. The ECU calculates engine speed from the time interval between the consecutive pulses. The two-tooth gap creates an “interrupt” input signal, corresponding to specific crankshaft position for PTO cylinder. This signal serves as a reference for the control of ignition timing by the ECU. On twin cylinder engines, synchronization of the CPS and crankshaft position takes place during the first two revolutions each time the engine is started. On single cylinder engines, synchronization also includes the Manifold Air Pressure Sensor. The CPS must be properly connected at all times. If it fails or becomes disconnected for any reason, the engine will quit running.
 

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Discussion Starter · #9 ·
My dealer got an official response from Polaris on my speed sensor. Polaris responded that this is normal since the vehicle is traveling slowly and the RPM is high. There is nothing that they will do. My dealer has noted the response in my file in case there are any associated issues that may develop. The dealer has done all he can do but I am not happy with the response from Polaris. From this response, I can only read between the lines that the Ace is not designed for rock climbing or trail conditions where you have to go slowly in low gear. I have one trail that the check engine light comes on every time I drive it. Buyers beware. A check engine light is a normal condition if you are driving slowly on an Ace for an extended period of time, like five minutes.
 

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Has anyone experienced a shutdown because of this, as said mine has come on a few times only when using L and other than the check engine light nothing else has happened, shift up to H and it goes out in a few seconds.
 

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Discussion Starter · #12 ·
js5020, so far my engine has not shut down. That is my concern. I ride in places that if the engine shut down it would be dangerous. I have a couple of steep rocky trails that are safe as long as you keep moving. Trying to start from a stopped position would be dangerous.
 

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thanks I sort of lost who or what aces were affected, Ithink half my gray matter is dead or at least taking a long rest
 

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I have the smaller engine on my Ace. It did the same thing to me.
Once I got on dry land and got my speed up, the light went off.
 

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This problem became apparent with the introduction of the 900 Ranger in 2013 with several reporting problems with the engine light and error code.
All of the Prostar engines use the same basic transmission design and they all use the same vehicle speed sensor # 4013908.
This error seems to be more prevalent on the Ranger and now the Ace, just from what I read on the different forums.
I suspect the problem is more in the ecu than in the sensor itself. JMHO
I have never read of anyone having an engine shut down because of it.
 
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