BRZ vs. Torque App & Cheap OBDII Adapter
 

I'll state up front that I learned car repair on old cars with carburetors, plugs and points, with nary a computer in sight. ECUs are a bit of an enigma for me. With that said...

I have a bone stock 2014 MT BRZ Limited. I've been running a cheap BAFX OBDII bluetooth adapter connected up with Torque to provide some of the gauges this car should have had on the dash. A couple of weeks ago it threw the U0073 code while I was pulling out of a gas station in rural Arkansas. The CEL and slip lights came on, and the car went into limp home mode with a huge loss of power.

I pulled off to the side of the road and looked up the code on the internet (on this site actually). For those who don't know, Torque (or that shitty BT adapter) is actually the cause of the U0073 code. I determined that it was no big deal and reset it. Then I was on my way with no discernible lingering effects.

Since then the ECU has thrown that code twice more. The second time it did it, I reset it again and had no lingering effects.

However, when it did it the third time Thursday, the car didn't quite recover and was sluggish afterward. I cleared the code, and the slip light was off. But for the remaining 300 miles of my trip it felt like the engine was only giving me 85% or 90%. You know that kick in the pants you get above 4K RPM after the torque dip with the stock tune? It was gone. The difference was subtle and was something only someone accustomed to driving this car would have noticed, but there was enough there that I'm sure it wasn't in my head. The car was still perfectly drivable. It was just a little off.

I let it sit overnight and drove it again yesterday, and it seems to be back to normal. Luckily my new not-cheap OBDLink adapter arrived yesterday, so I can ditch the BAFX adapter and see if that solves the recurring U0073 problem.

However, I would like to know what happened after I cleared that code that last time, and why it didn't completely recover. It seemed to me that it should have gone back to normal after the code was cleared.

Can any of you guys who are whizzes with the computer tell me why it did that?

Apparently the BAFX adapter wasn't the culprit. I had to reset the U0073 code twice this afternoon, and the car is sluggish again. I took it off the highway and romped on it a bit around town, and it seems to have recovered some--but not all--of its mojo.

I'd really like to know what it's doing. I'd also really like to figure out if there's a trick to avoid throwing that code in the first place.

You will get that code if you leave the torque app running and you shut the car off and start it back up shortly after like stopping for gas. If you quit the torque app before starting the car back up you wont throw the code anymore.

Sent from Samsung Galaxy Note 3

What I think the trick to not getting the u73 code is to not have the torque app running when you turn on or start the car.

I used to get that code all the time when I had a tablet running the app but after I got my android radio to run torque I haven't had that code come back ( knock on wood ) and iv ran it about a year now.

Hope that helps.

can anyone tell me why torque would do this? ive had torque and a shitty bt adapter since day one and i have never had this issue.

Ive had this issue with a similar setup, (cheap bt obd reader, torque) and it threw a code in the middle of driving my car, not just start up. I was told to buy an expensive bt device but wasn't sure if that will fix the issue..

I have an FRS with 300km on it and I have an expensive BT adapter. I got this code after stopping and starting as described above. I feel comfortable that this is what caused the code. I'll be more careful with Torque running from now on.... Thanks guys.

Then, it wasn't expensive enough.. duhhhh

This is the reason - always start car with Torque off (unconnected to BT). You'll get U073 with it on and it'll set a rev limit of 4K (IIRC) on your car until its cleared. As far as I know, it's a communication error. Perhaps ECU doesn't expect comms through the OBD port on startup and flags it as an error. I think it's harmless.

Since I originally posted this, I have been making sure Torque is shut off every time I shut off the car, and I haven't had a problem except the two times I forgot to shut it off. Both times it threw the code as soon as I started the car. It has nothing to do with how expensive the adapter is, since I have a cheap one and an expensive one and see the problem with both.

I still don't understand why the car continued to be sluggish after the code was cleared. I would think that once the code is reset, engine operation should return to normal.

I had this happen to me once, I have a feeling the program resets the ECU to reset the code because my pedal was not accurate for about 50 miles as if I unplugged my battery.