Help with code P1720

[Cisc0]

Cruising my X shuts off on me and "Trans Fail Safe" kicks in along with all the christmas lights on the cluster. I park and turn off. Wait a few mins and try to turn back on, after is on all seems fine, I drive a block and boom same sh*t. Pull out the code reader and the code I get is: P1720. Did a search on here but to no avail. Did a google search and came up with this:

Local CAN bus

The CAN bus (Controller Area Network) is a serial bus system, in which all connected stations are equally entitled, i.e. each control unit can both send as well as receive. In other words, the connected control units can "communicate" and exchange information via the lines.

Due to the linear structure of the network, the bus system is fully available for all other stations in the event of one station failing. The connection consists of two data lines (LOCAN_L and LOCAN_H).

The local CAN bus exists independently of the familiar CAN bus. The local CAN bus serves only engine functions. The data exchange across the Local CAN bus takes place between the following control units, depending on the engine variant:

DME control unit

Valvetronic control unit

HDEV control unit

The connected control units must all have the same CAN status. The CAN status can be checked via the diagnosis interface. The CAN status (bus index) is specified on the identification of the relevant control unit connected to the CAN bus


I'm guessing one of the three Control Units above failed to boot up properly.

A lil more info to try a narrow down. About a less than a month ago I had my DME replaced with a used one and coded to my vehicle due to an electrical shortage caused by a screw in my A/C's wire harness. Can this possibly be a lead to what the culprit is? Can someone who's encounter said code shed some information on your experience please.

I will be taking the X back to the shop that performed the coding on the DME first thing in the morning.

Thanks in advance for any replies.

[Big "J"]

Haven't had that code before but, off the top of my head...how old is your battery? Low voltage to the control units will cause weird stuff to happen. Check you battery and it's terminals.

Good Luck!!

[Cisc0]

Battery was replaced last year. I rule that out, but anything is possible. I was also thinking alternator.

Thanks for the reply.

[Cisc0]

So I head out this morning. Turn on the X and the bitch fired right up. 45min drive to Indy and no fooking issues. Get there, hook up to GT1, comes back with the local can bus code (DME issue) and a EWS code. Turns out DME and EWS were not communicating. Tech says he sees no issues after driving it. Clears codes and tells me if they resurface I may need to leave it for further diagnosing. I get back on highway doing up to 90mph and no issues. I swear my X is possessed.

[SlickGT1]

Drive while having your obc read out the voltage. It's not possessed, it electronically screwed.

[Cisc0]

Originally Posted by SlickGT1

Drive while having your obc read out the voltage. It's not possessed, it electronically screwed.

They did and voltage readings were fine.

[SlickGT1]

Yes they did it, and you have had no problems since. Now you unlock your OBC. After that, its just one button to watch your voltage every time you drive. Next time it happens, lets hope it doesn't, you might have a clue as to whats up.

[Cisc0]

Originally Posted by SlickGT1

Yes they did it, and you have had no problems since. Now you unlock your OBC. After that, its just one button to watch your voltage every time you drive. Next time it happens, lets hope it doesn't, you might have a clue as to whats up.

Everything has been working as it should so far. Possible culprit according to tech is that the EWS is failing but will not know until it happens again (hope not).

if possible can you lead me to where I can find steps to unlocking obc so I can add the voltage function.

thanks in advance.

[Cisc0]

Originally Posted by Cisc0

Everything has been working as it should so far. Possible culprit according to tech is that the EWS is failing but will not know until it happens again (hope not).

if possible can you lead me to where I can find steps to unlocking obc so I can add the voltage function.

thanks in advance.

NVM. I found it. Unlocked the shizz and the highest I got was 13.8v to lowest 13.3v(while at stop light). I kinda like this unlocked obc thing. I giggled like a school girl once I saw the voltage. Wish everything else was that easy.