CEL U0074

[kevroq]

Hey guys,
My 2015 BRZ (11,000 miles) threw check engine light U0074 last night. Did not notice it run any differently. It was my second day with a Bluetooth OBDII reader running the Torque app on my tablet. I disconnected the OBDII sensor after reading the code and it did not disappear. The next day it was gone without me having to clear it.


Code U0074
"Control Module Communication Bus "B" Off"


Do you think that the OBDII reader caused this or know any more information about the code? I used torque to read the code as soon as it happened.

[Icecreamtruk]

Did you disconnected the OBDII bluetooth reader while the car was running? (or maybe wiggle it or hit it with your knee or something?) Because if you do it will throw a code. To avoid codes related to this, you can connect the reader with the car on, or off, doesnt matter, but only disconnect it while the car is off.

[extrashaky]

This is a known issue caused by Torque. If Torque is already running on your device when you start the car, the car thinks there's a communication problem and throws U0074. It's harmless, but it does put the car into limp mode when that happens, cutting out your air conditioner and cruise control and limiting the performance of the car. If you drive it with the code showing, it will get sluggish and take a few days to recover after you clear the code.

If you throw the code, just clear it with Torque as soon as possible and drive. To prevent it, be sure to remember to exit out of Torque when you shut off the car by clicking your "back" button until you see the message that says, "Quit Torque - Are you sure you want to exit Torque?" It is not necessary to remove your bluetooth adapter or turn off the tablet as long as you completely exit Torque before starting the car again.

I tried to use Tasker to set mine up to automatically exit Torque when it disconnected from the car but couldn't get it to work consistently. Now I've just gotten into the habit of turning off Torque every time I get out of the car.

[kevroq]

Thank you, what you both said makes complete sense. I was hoping that it was a harmless CEL caused by it and now I know how to avoid it. Ill start looking into ways to close torque automatically with the vehicle shutoff. Not that its not easy enough to turn if off every time but I like solving these problems haha. Ill report back if I find anything

[Icecreamtruk]

If you know how to create android apps, you could create an android app that can run on the background and detect when a bluetooth device disconnect and Torque is running and then closes Torque. Shouldn't be that hard IF Torque allows other apps to communicate with it.