Dear Ralph: I have a 2007 Ski-Doo MX Z 600 HO SDI. When I was adding oil the other day, I noticed a wire...

Dear Ralph:
I have a 2007 Ski-Doo MX Z 600 HO SDI. When I was adding oil the other day, I noticed a wire going into the muffler. What is this? I figured it might be a temp sensor, but that doesn’t make any sense, either.

Yes, the wire running down into the muffler is indeed a temperature sensor. This is one of the many inputs that is being analyzed by the on-board computer (ECU) as it keeps the engine running properly.
A muffler temperature sensor is different from an exhaust gas temperature of the tuned pipe. The sensor in the muffler of an SDI engine is a safety device to prevent the muffler from overheating. This is really only needed in lean-burn engines like the SDI. If the muffler gets too hot, the ECU will go through one stage of trying to cool itself down, before dropping to a limp home mode. During “normal operation” it does absolutely nothing.
Also of concern is unburned fuel entering a hot muffler, going “BANG” (the backfire when you turn the sled off). This is why, after a good hot run, you should always let your sled idle down for a few seconds before hitting the kill switch. If you come in hard and quickly turn the engine off, there will be more fuel coming through the exhaust and when it gets to a cherry-hot silencer, this is where the “BANG” can come from. This holds true for all two-strokes; you really should let them come down to idle before cutting the ignition.

  • Tim Solis

    December 28, 2007 #1 Author

    I have a 2006 600 Rev HO SDI that I just bought with 1200 miles. I never had a chance to ride it with the sock muffler on it. I bought a BPM Muffler with a Temp Sensor Port. I ran this for a few rides. Eventually, the harder I rode (Faster) The engine started to cut out at around 7,000 to 8,000 RPM. I then took off the can and reinstalled the stock muffler. It did not fix itself, so I had a dealer hook it up to the laptop. A code came up for exhaust heat. He cleared it. I have not had a chance to ride it yet, but he thinks that did the trick. Do you think I need to replace the sensor as well. And, if it ever went into a limp home mode, can the temp port be plugged to get you home a little faster.


  • snow man

    July 17, 2008 #2 Author

    so it sounds like disconnecting wires to exhaust can temp sensor will keep it from going into the cronic limp mode. If the cumputer senses that it is disconnected,maybe leave the old sensor in place and purchase a new sensor. hook up the wire to the new sensor that is ty wraped away from the exhaust can that gets cherry more dam limp mode.

    to bad they could not just have a software program that will richen up the mixture which you claim is the problem in the first place.

  • Jordan rooney

    March 27, 2015 #3 Author

    i have an 05 sdi 600, changed 2 exhaust tempereature sensors in 2 years, not sure if it is their fault or im having bad luck… the next time it goes i think im going to replace it with a 470 ohm resistor see if it solves the problem, cant keep buying them at 240$ a hit

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