Wrench light on, cold start.

[AZ_Ryan]

What is it supposed to be at?

Generally speaking, most cars run 13.5v-14.5v during normal operation. Some fluctuation is normal depending on what accessories are running. Anything under 13 means the battery isn't charging adequately. 12.7v is what a healthy battery should read at rest.

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[K4fxd]

Ford's battery management will allow battery voltage to fall below 12.7 while running.

Don't pay any attention to your volt gauge.

 

[AZ_Ryan]

Ford's battery management will allow battery voltage to fall below 12.7 while running.

Don't pay any attention to your volt gauge.

While running???That's a new one on me. I've owned 2 S550s and I've never seen it go below 14v. How do you know this?

 

[K4fxd]

How do you know this?

It's part of the battery management system. It totally shuts off the alternator at random or what seems to be random times. First time I saw it on mine I freaked, then I learned Fords battery system. Then I learned how to shut Fords management system off.

IMO, If it were better then we wouldn't hear of so many battery replacements under 3 years. My stock battery lasted about 2 years, the replacement, after I changed the Battery management settings is now on it's 4th year.

 

[Garfy]

It's part of the battery management system. It totally shuts off the alternator at random or what seems to be random times. First time I saw it on mine I freaked, then I learned Fords battery system. Then I learned how to shut Fords management system off.

IMO, If it were better then we wouldn't hear of so many battery replacements under 3 years. My stock battery lasted about 2 years, the replacement, after I changed the Battery management settings is now on it's 4th year.

Actually it depends a lot upon the battery quality. Many Honda OEM batteries that says on it that it has a 100 month warranty barely last 3 years, many fail at 2 years (this from a Honda parts manager). Yet after I replaced my Honda battery with an Interstate MTP-151R which had a 5 year warranty, it actually lasted almost 6 years before I had to replace it. So far, my 4 year old S550 still has the original battery in it and it's fine thus far, though when I last tested it with my battery tester it came up with about 560 CCA which is below the rating so it's probably going to be failing sometime soon.

 

[MiamiGT350]

That voltage is too low when running. Get your battery checked ASAP.

This is not correct. The battery charge is managed via the Battery Management System (BMS) and it will smart-charge to extend the battery life. It is completely normal to see it fluctuate. If you want to know your battery voltage, put the car in accessory mode without starting the engine, and view the voltage output in the dash.

@Metz3020827, when my friend's throttle body was going bad, he would get a wrench on the dash randomly. Each time we would scan, we would end up with no codes. It took about 10 times before we were able to get a DTC from it.

My suspicion would be that this is a one-off due to the cold weather. You should really only worry or be concerned if the wrrench issue returns.

 

[SIC1SIX]

How old is your battery? If it’s older, it may be starting to go and the car will start doing weird things. It does not like a low battery. Most auto parts stores will do a free battery health check, might be worth stopping and having it checked out.

That would be my first thought if it’s not throwing an actual code

Yep. That happened to me once... turned out to be a weak battery

 

[Silver Dragon]

I have got the wrench light to illuminate once on a cold start (car lives outdoors).Switched car off and it didn’t come back on again.Very helpfully (ha ha) it says check the owners manual which is a complete dead end. I had recently just replaced the original 7 year old battery.

Discussing it with my specialist over the phone they said it might have been an ambient temp sensor fault?

in OP post it mentioned a fairly cold start ?

 

[Metz3020827]

I have got the wrench light to illuminate once on a cold start (car lives outdoors).Switched car off and it didn’t come back on again.Very helpfully (ha ha) it says check the owners manual which is a complete dead end. I had recently just replaced the original 7 year old battery.

Discussing it with my specialist over the phone they said it might have been an ambient temp sensor fault?

in OP post it mentioned a fairly cold start ?

Yep. Mine hasn’t come back.

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