FYI - Plugged in Block Heater can trip the Check Engine Light -
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Unread 01-12-2010, 11:29 AM   #1
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2008 MK Compass 
Join Date: Feb 2008
Location: Winnipeg, MB, Canada
Posts: 227
FYI - Plugged in Block Heater can trip the Check Engine Light

We've had that annoying little Check Engine light come on a few times last year during winter, and now once again this year.

We brought it by the stealership and apparently, if you happen to start the car while your car is still plugged in, it can upset the Jeep's computer. It's been a known problem with the '08s. They ended up flashing the computer to update the firmware.

I admit, I normally start the car, and then go unplug it. Sometimes I do it the other way around. I've never known it to be an issue before. Although now that the computer is flashed, it's supposed to be alright now.

Just thought I would share the experience to fellow MK owners - especially those with the block heater.

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Unread 01-19-2010, 01:05 AM   #2
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Mine must be flashed already, none of that problem here. I start mine with the autostart everyday and no issues so far.

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Unread 01-19-2010, 09:26 AM   #3
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2015 MK Patriot 
Join Date: Mar 2009
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When we first got our Patriot I didn't think the block heater was working because it was so quiet compared to our Cherokee which makes a noise as soon as you plug it in. I took the Patriot to the dealer and they tested the block heater and said it was working just fine. I also use synthetic oil which makes starting in the winter a little easier. The only time I have ever seen the MIL light was during mid-summer in Illinois and I think it was a bad tank of gas. The light went away on our next fill up.
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