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Dead Battery/Check Engine Light


jo137649

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I have a 2008 GT500KR and I went out of town for a month and the battery was completely depleted when i tried to start it up when i got back. After i recharged the battery i was able to start the car ok but a check engine light came on and stays on. there is no guidance in the supplements on what to do to remove this engine light. The car runs great and i even did that idle relearning that the main mustang manual tells you to do. Could it possibly be that my sensor is being tripped by my CAI? Please help!!!!!

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If it's an intermittent fault code caused by the dead battery and there are no other outward issues with the car's drivability, then you can reset the fault code by disconnecting the NEGITIVE cable from the battery for about 15 to 30 seconds, reconnect it properly, and that should clear the fault code. If it doesn't, then take the car into the dealer so they can find out what the problem is.

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If your running a aftermarket CAI with out a tune, it will set a lean code. You may also have a code from a completly dead battery "system voltage low". Disconnecting the battery does not clear codes as in the past. Get it checked too be sure.

 

That's odd; my 2007 does.

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You may be correct. But alot of the vehicles I deal with daily will not clear the codes with battery disconnecting. Have to clear the out with the lap top scanner anymore.....

 

Oh, I absolutely agree, but I have been fortunate to be able to clear an intermittant fault code by DCing the negitive cable on my car. I completely support the idea that any code should be investagated via a laptop in order for it to be resolved properly, but in my case I knew what the cause ( it was a bad clamp on my CAI where the air cleaner connects to the flow tube) of my light was so I was not concerned about clearing the code when it popped up.

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If your running a aftermarket CAI with out a tune, it will set a lean code. You may also have a code from a completly dead battery "system voltage low". Disconnecting the battery does not clear codes as in the past. Get it checked too be sure.

 

 

 

The CAI that is in there is the one installed by Shelby during the KR conversion (Ford Racing). It was definitely tuned at the factory when installed, i was just wondering if the system needs to be retuned everytime the battery goes dead(if the latter, Shelby did the tun so i dont have the tuner-how do i get it from them?). Do the dealer's techs have the ability to reset the code via laptop? If the code indeed is a "system voltage low", will that go away on its on after a few drives?

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The CAI that is in there is the one installed by Shelby during the KR conversion (Ford Racing). It was definitely tuned at the factory when installed, i was just wondering if the system needs to be retuned everytime the battery goes dead(if the latter, Shelby did the tun so i dont have the tuner-how do i get it from them?). Do the dealer's techs have the ability to reset the code via laptop? If the code indeed is a "system voltage low", will that go away on its on after a few drives?

 

The easy answer to your question is no, you don't have to reflash the computer whenever you battery dies. The program is held within the memory and can only be lost if someone goes into the data port and writes over the CAI tune or if the system has a severe short, and I mean severe (like ARC welding on your car without following proper procedures to protect the computer).

 

And if that does happen, your dealer has the ability to re-install the tune back into your car.

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The easy answer to your question is no, you don't have to reflash the computer whenever you battery dies. The program is held within the memory and can only be lost if someone goes into the data port and writes over the CAI tune or if the system has a severe short, and I mean severe (like ARC welding on your car without following proper procedures to protect the computer).

 

And if that does happen, your dealer has the ability to re-install the tune back into your car.

 

 

Thanks for the info Sir. I am going to take it into the ford dealership to have them triage.

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Thanks for the info Sir. I am going to take it into the ford dealership to have them triage.

 

:salute:

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you go to the auto store and buy a OBD2 Code reader for like 60 bucks.

and erase code on your own instead of running to the dealer every time a light goes off.

But if the light continues to return, with the same code then i would go to the dealer.

Rite down the codes and look them up on the internet. then clear

 

i has one

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If it's an intermittent fault code caused by the dead battery and there are no other outward issues with the car's drivability, then you can reset the fault code by disconnecting the NEGITIVE cable from the battery for about 15 to 30 seconds, reconnect it properly, and that should clear the fault code. If it doesn't, then take the car into the dealer so they can find out what the problem is.

 

 

Son of GT- You called it. I tried your recommendation of disconnecting the negative cable from the battery for 30 seconds and IT WORKED (i have a 2008 GT500KR)! Im sure this only works (remove check engine light on 2006-newer mustangs) in the case of a bad battery and not any other powertrain issues. Thanks again my friend.

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i would always recomend having the code read on the car. why even take the risk on a 50K plus car. if you can spend that kind of money you can spend one on a ODB2 reader. ford will read it for free if under warenty

 

 

 

I already have an appointment to do so. I was just worried that it could have been something worse which a negative post reset would NOT clear a check engine light as that failure would remain according to SVT. It only has 1000K miles on it and hasnt been pushed at all as im still breaking it in (bought it in July). Yes it is under warranty-thanks for the advice.

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I already have an appointment to do so. I was just worried that it could have been something worse which a negative post reset would NOT clear a check engine light as that failure would remain according to SVT. It only has 1000K miles on it and hasnt been pushed at all as im still breaking it in (bought it in July). Yes it is under warranty-thanks for the advice.

 

 

still ford needs that check engine light to pull the code to see what it is. it prolly was nothing big, next time just buy a OB2 scanner an check it out 1st.

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