I started up my truck this morning and the engine light came on...I am taking it to Dodge this next week for the 21,000 mile service. I was a bit concerned so I went to Auto Zone to have them use their code reader to see if this was a serious enough problem to warrant dropping it off and getting a rental to get me by as service is closed on Sunday. The code reader stated U1120 "check service manual". The code reader seems to have reset the engine light.
I read a post about this code sometime back. I believe someone told the guy it was a serial comm issue with the ecm. I think this caused his horn to blare and lights to flash in his particular case. My truck is behaving just fine other than my worry due to the light coming on.
How can you reset the ecm??? Is a code reader the only way to do so? Should I buy a reader? And if so, which one would be recommended? Should I buy a service manual from Dodge as well?[]

 

touch the battery cables together unhooked from the battery. Or jus tunhook the battery and turn the light switch on itll eventually drain any excess electricity and clear the ecm

C.E.L's are nothing to freak out about unless there blinking, half the time if not more its something stupid.

 

Thanks for the info

 

I would suggest taking it and getting it looked at or at least running the code yourself. My CEL came on probably a month or two after buying my truck...so being very cautious I decided to take it in to the dealer and the service writer told me that it was nothing to worry about since it wasn't blinking and that it would clear itself within a couple days. Well a couple days come and go and the light doesn't go off so I go back and they actually take the time to look at it and discover it was a simple malfunction that took about 20 seconds to fix.

So, about two months ago my CEL came on again and taking the advice of the wonderful service advisor before I waited for about a week before taking it in, mind you it again wasn't flashing, and when I took it in the service manager and a different service writer told me that I should never wait to have my CEL checked and that this time it was caused due to a valve malfunction on my exhaust and was causing problems. The problem was fixed and I got nearly a 2 mpg increase.

 

Waiting a week for it to clear is usually BS, unless it came on right after you filled up. (The amount of cels causing by gascaps not being properlly closed is shocking). But yeah if its not blinking its not life and death

 

LOL....a week....

They're just saying that because they don't wanna see you back so soon again complaining about something else.....ha ha

 

Seriously...that's why