I have an 05 Chrysler 300 that has been having a reoccurrence of p o 700 code pop ups. The drive is somewhat normal, no odd shifting, or issue with mph, but i feel like it could be faster, possibly it’s not going it’s full potential? The car is in really great cond 40,000 miles original.. last week my oas epa brake light went on, then disappeared hours later without reappearance. From there on, my brake light came on would turn off and then my check engine would appear after things appeared normal. Today i drove to work about 20 minutes away and both my check engine and brake light went on . I’ve since today went to have a engine check and it says trans error code po 700. A “mechanic” has quoted that i change my coils and spark plugs ($600 quote) then likely follow up with a repair of the transmission modulate and quoted me 3 days of work and $1300 est charges. But wait - I drove the car for about 30 minutes longer and noticed both lights are now off, and car is driving smooth and normal. I’d love to hope that this code stays off but i expect it to return within my driving the next few days. Any idea to lead me what’s going on here?

 

You do not change coils for a code P0700.
700 is a generic code that pops up on cheaper scanners to let you know that there is a deeper transmission problem, A good scanner would then be used to read the exact code from the system.

Most often when a Chrysler 300 starts throwing random codes that disappear, and change like that, it is due to a defective, or worn out battery.
These cars require a good battery to work correctly because pretty much everything in the car is controlled by the computers in it.
Have the battery and alternator checked out to make sure that the Alternator is putting out just over 14 volts when the engine is running, and that the battery can still hold a good charge.
Many auto parts stores have the equipment to do that for you, either cheap or for free.

 

Oh, and if the battery and alternator both show as being good, check the ground cables and make sure they all have a good connection.

Please come back and let us know the outcome, and if turns out to be that what I said was correct, do not go back to that mechanic again.

 

BiliTheAxe thank you for your advice. I just left a private local auto shop that was recommended to me and i had them check the battery, it’s showing it has full power on 14 volts from the alternator. This mechanic was very honest, and in short, he test drove it and inspected anything else he could think of, resulting in the car drives really well, and although there is no check engine light on this moment , he went through my code history and seen the P 0700 listed 3x. He told me just keep an eye on it, ( as of right now there is no maintenance needed for any parts) and if the code comes up again he has a transmission shop to send me to... the prior place i went to was corporate company pepboys and i now know they have a quota of parts to sell, so the guy was just trying to do his job and encourage selling things. If you have any other recommendations otherwise i will stick with watching out for this code to return.

 

Those other issues you had pop up still make me think the issue could be electrical, so if you get the 700 code again, and take it to a shop, ask them to check the ground cables on the car, before they start tearing into the transmission.