2005 A4 B7 Starts Then Immediately Dies

[TGreen13]

Hello all, I am new to these forums so bear with me. Allow me to give as much detail on my A4 dilemma as possible. Roughly a year ago I purchased a 2005 Audi A4 B7 model to work on with my daughter as her first car. I was able to get it quite cheap as it was in need of a new transmission and some mild interior and body work. Here is what information I have on this vehicle:

-2005 Audi A4 B7
-Front wheel drive (HHE CVT Transmission)
-2.0L Turbo
-Engine started and appeared to run fine when we bought the car
-Transmission made noises when shifted into any gear and would not move

We pulled the front end off of the car and removed the engine and transmission together. This allowed us to clean the engine up replace gaskets as needed. We swapped out the transmission and put everything back together. It may be important to note the battery was out of the car for roughly two months while we performed this work. When we went to start it for the first time after replacing the transmission it will start then immediately die. This has continued to be my problem since. Some observations we made while attempting to diagnose:

-The dashboard center readout panel states “Press clutch to start” but it’s an automatic.
-When connecting OBD scanner, we use OBDeleven, it states there is no connection

Any thoughts or recommendations would be greatly appreciated. This has become quite a challenge and was hoping to avoid a trip to the dealership if possible. Thanks in advance

[Der Konig]

Sounds like you toasted your ECM potentially through a bad or disconnected ground.

So no communication to the ECM? IF you had VCDS it would be nice to see if you can talk to other modules such as ABS and such. If you can talk to others and not ECM, your ECM is probably shot.

IDK anything about this program obdeleven you are referring to, can you try to talk to anything else with it?

[TGreen13]

I do not think the OBDeleven tool can talk with other devices. Honestly, I am still working through it but I did hook it up to my dodge to double check that I didn't just have a faulty scanner out of the box. I have put a link to their home page if you're curious. My fear is that somewhere along the process the ECM was damaged. Do you know of any way to test the ECM? Some folks I have spoken with stated that I may need to have the ECM reprogramed to recognize the new transmission and have pointed me back to the Audi dealership for that.

https://obdeleven.com/en/

[Der Konig]

I do not think the OBDeleven tool can talk with other devices. Honestly, I am still working through it but I did hook it up to my dodge to double check that I didn't just have a faulty scanner out of the box. I have put a link to their home page if you're curious. My fear is that somewhere along the process the ECM was damaged. Do you know of any way to test the ECM? Some folks I have spoken with stated that I may need to have the ECM reprogramed to recognize the new transmission and have pointed me back to the Audi dealership for that.

https://obdeleven.com/en/

I can't see that being the case, it shouldn't have forgotten its an automatic. I don't know any other way of testing it besides trying to talk to other modules, if you can but not the ECM then its toast most likely.

When you put the car in the accessory position, what dash lights come on? Does the CEL light come on in accessory?

Looking at their website, it looks like you may only be able to read trouble codes. When I had ECM issues I was able to use VCDS and go into the ABS module then press on the brake pedal, this allowed me to watch the pressure respond and confirm I could talk to other modules.

- Read and clear diagnostic trouble codes from all control units that is installed in your car (i.e. Engine, Transmission, ABS, Airbag, Multimedia, Air conditioning, etc.)
- Multilanguage database
- Read information about control unit (i.e. Part number, Software number, Coding, etc.)

The fact that it can read and clear all the trouble codes from other modules leads me to believe there's got to be a way to do some kind of basic comm with other modules. Even if you can just connect to the air bag module or something.

[SamsonKnight]

Possible lost key program?

[joepickems]

im staying out of this thread considering i have no idea whats going on

[Der Konig]

Possible lost key program?

Could be the passive anti theft but typically that would result in just cranking and no start. Theft should also blink I believe.

Sent from my SM-G935V using Audizine mobile app

[TGreen13]

Thanks, I get no check engine light, or any errors actually, other then the what I assume is the standard startup air bag, traction control, and battery lights when I switch the key on. I finally broke down and called our local Audi dealership and explained my situation. The service rep said it sounded like I would need to have the computer reprogramed to accept the new transmission and made it seem like it may be an easy repair. Apparently each transmission has a unique number assigned to them that must be programmed into the ECU before it can see the transmission. Looks like I am going to go that route and hope for the best. Thanks again for all the feedback

[Nollywood]

Could be the passive anti theft but typically that would result in just cranking and no start. Theft should also blink I believe.

It does sound like an immobiliser issue.

If immobiliser is active, the engine will start, and run for a second, before shutting down. Possibly somewhere along the line, the key and instrument cluster are unpaired.

It’s worth noting the TCU for the CVT transmission is embedded in the transmission, and if you replaced it, the TCU will conflict with the ECU, as they will no longer match.

[Der Konig]

It does sound like an immobiliser issue.

If immobiliser is active, the engine will start, and run for a second, before shutting down. Possibly somewhere along the line, the key and instrument cluster are unpaired.

It’s worth noting the TCU for the CVT transmission is embedded in the transmission, and if you replaced it, the TCU will conflict with the ECU, as they will no longer match.

Interesting, didn't know they were unique. Good info. Maybe my PAT experience was different since it was actually APR's PAT programming kicking in.

[Silveravant]

I had the same thing happen with my 2000 Jetta after the battery died. With fully charged battery would start then die. I finally disconnected the battery and touched the cable ends together. After reconnecting the battery it started just fine. May not work, but worth a try.