WTF is this bullshit now

and what does it affect?

 

A "U" code is a network communications error code. It usually means an error occurred when a certain module or sensor tried to communicate with another one. As you know, there are numerous modules within a vehicle nowadays which all communicate with one another, with the PCM being the main control module.

 

Where do I even begin to look for problem

 

Bring to the dealership where they can take a Tech2 to it It's hard to diagnose stuff like that if you don't have manufacturer level diagnostic equipment. What symptoms, if any, are you experiencing with your car?

 

honestly none, Ive had a CEL for o2 sensor since August, I got my craftsmanCAN OBD2 yesterday and erased all o2 codes then this morning, after fullly warmed up, i floored it and shifted and it came on. Never had it come on before, if it comes on again I'll bring it to the dealership.

 

Control module communication bus off

Need a tech2 to pinpoint

 

Sometimes you can get a code from say having a certain sensor unplugged while the key was turned on or the car was started/running. I wouldn't worry about it unless the car starts exhibiting some symptoms/problems and the code comes back.

 

I'd figure the car would put itself into limp mode before it would allow damage to occur

 

Yea that makes sense

It tells you when it is in limp mode right. It's called like "engine power reduced"

 

Correct.

 

And I think u get a light on the dash too. Looks like a cell with a down arrow

 

i erased it but its going to bug the **** out of me now

 

Has to do with instrument cluster doesn't affect performance. Called up onstar

 

sorry for the bump but if you plug the scanner in while the car is on, could it possibly throw a code from that?

cause youre suppose to do it when the car is in the on position but not fully on

 

Plugging in a scanner should not throw a code. I really wouldn't worry about it at all.

 

Mine freaked out on time on me going to work. I cleared the codes and havent seen it since. I forget which one it was but it was a pcm/bcm communications code. I cleared it and luckily it hasnt returned. These cars seem to get a burr up their ass from time to time. They get all emotional like a woman on her period and then they randomly stop being bitchy and start showing you some love again... Don't worry about it dude. If it was something serious it would throw a fault code again pretty quick

 

...this is what happens to my car, very random, happened 5 times so far in 2013, and it gave me this code. u0073 ..thoughts?

 

^^BCM is my guess.

 

That happened to a buddy of mine's 2008 Sport. He unhooked his battery for 10 minutes and then it never happened again. my guess if its doing it consistently its a bad BCM

 

The GMLAN serial data circuits are controller area network (CAN) high and/or low speed serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained. There are two different types of GMLAN serial data circuits, the High speed 2-wire circuit and Low speed single wire circuit. Refer to Data Link References for the complete description of the buses used on this vehicle. The GMLAN serial data circuits also communicate directly to the data link connector (DLC). Messages are interpreted by the externally connected CANdi module which acts as a transceiver for the scan tool.

Modules connected to the GMLAN serial data circuits monitor communications during normal vehicle operation, where operation information is exchanged among the modules. All the modules on the GMLAN networks, maintain a transmit error counter (TEC) and a receive error counter (REC). The counter values increase with detected errors and will decrease with error-free messages. If the TEC value exceeds 255, the controller removes itself from the network and DTC U0073 will result.

 

Have you tried disconnecting your battery? My car was acting up really bad a few days ago. All my gauges would randomly shut off and come back on and the traction control light and ABS lights would come on then shut off in 10 second intervals. It was really wierd but when I disconnected the battery it didn't come back.

 

I had a U0073 occur when I got a short in my scan gauge cable I had connected to my OBDII port a while back. Disconnecting the cable caused everything to immediately return to normal.

I'd suggest unplugging anything that's plugged into your diagnostic port (and the RPD, if you wired one into yours). If it still does it, then I'm betting it's a short in the wiring, probably something near the OBDII port that got rubbed/chaffed.

Here's what mine was doing.

 

I agree with the above. I'm guessing the scanner you bought made the OBD2 port go bonkers.

 

Confirmed. My cruise control has an effect on the code. 90 percent of the time when i use cruise, the U0073 code triggers. sometimes within 10 minutes, other times with in 2 hours. Ideas?

 

I had a U1300 code on my Saturn S series. Not directly related, but the U code threw me off. After some troubleshooting, I ended up replacing the airbag sensor ($15 on ebay – woohoo) which fixed the code. If each sensor (typically unrelated to the engine or transmission since those are P codes) is not talking back to the computer, it will throw a U code.