[ischmitz]

I don't know the meanings of any error codes of the Tiptronic computer. Are you sure the #24 comes from the Tiptronic and not from the DME. What is the explanation from the Durametric for that error?

What I do know is that when the tiptronic computer initiates a shifts it sends a signal to the DME to momentarily retard the timimg. This is to reduce the torque flowing through the gear box for easier shifting. I could see that the DME doesn't properly process that signal with the knock sensor being bad and timing already being retarded. However, to my knowledge there is no way for the tiptronic module to "notice" that the shift signal wasn't properly acted on by the DME. So I don't know why the tiptronic would throw up a fault code.

The Motronic uses two knock sensors (one on each bank of cylinders) to check for knocking. There is an aluminum bridge mounted to the cylinders and the knock sensor sits in the middle of that bridge. It acts like a microphone. Once knocking is detected the ignition for that cylinder is retarted to prevent further knocking. This is a feedback loop.

The knock sensor is a piezo-electic sensor that generates a small voltage spike when it gets deformed. There is a special screw for mounting the sensor and you need to follow the mounting specifications (torque) precisely to make sure they work. They are located under the black plastic engine shroud. You might get to them when you remove the alternator/fan. Not sure if the intake and shroud can stay on but I think it should be feasable with it still in place.

If knock sensors #2 is not working the DME will issue fault code #1_32 (knock signal not plausible) and the ignition will be retarded by 6 degrees to prevent damage. You will notice a loss of power, too.

The O2-sensor is easy. If the sensor voltage "seen" by the DME is less than 0.1 Volts or more than 1.0 Volts and error code 1_24 is generated and the system will not use the O2-sensor driven closed loop system. Replace the O2-senor. These sensors age with time. It could also be a bad connector with faulty contacts. If you unplug and re-plug it a couple of times it might solve the problem. The connector is located in the engine bay on the left side. It is a black round thing towards the back. You might have to do some searching. Try the same for the knock sensor. I don't know which one is which but the connectors are green. One is on top of the intake and the other is on the bracket on the left side of the engine where the vacuum and fuel lines go. They are three-pin if I remember correctly. Unplugging and re-plugging cleans the contacts.

Hope that helps,
Ingo