Hi all, hoping for some guidance.

Daughter has a 2001 Astra TS CD, Auto. Still a nice car given the age, neat, tidy, drives great (or at least used to!) and only 106000 km. It recently developed an issue of the Traction Control Light illuminating, at times accompanied by the Emissions light and usually Limp Mode. A few fault codes to go with it. Usually accompanied by a noise (whine) from the passenger side of the engine bay (transmission area perhaps?) which lasts for a few minutes after start up and disappears. The thing is still driveable and performs fine by manually selecting gears.

Whilst the faults are usually consistently occurring, at times can start the car and they don't exist, then kick in after a couple of minutes. The noise I mentioned kicks in at the same time...and goes away after a couple of minutes. Whether it is the cause of the errors or created by an electrical/ECU/TCU issue is a ?

So it's been to a mechanic and referred to an auto-electrician. The result has all been inconclusive. Auto-electrician's advice was that based upon codes and past experience with Astra's (not that complimentary about the electrics!) it could be a few things - TCU, ABS Ctrller, ECU?...lots of time and money could be expended without solving and it wouldn't be worth it for the value of the car. I am struggling with scrapping the car given it's condition so want to have a crack at sorting it myself. Logic says to me that not all of the possible causes could occur at the one point in time so starting with the ECU seems to be the way to go.

So I've done a fair bit of research on-line to see what I could learn and try and would appreciate some info from those that may have been down the path before, particularly:

1. In regards to a second-hand ECU, do I need to try and find one with an exactly matching number, and what do the numbers on the unit mean? (GM Siemens, 09 158 670 / S 01 001 08 / 5WK9 153)

2. Opcom seems to be the software to use. I've concluded that I'll need a diagnostics interface/USB adapter like the one at the link below for Opcom on my PC to interface with the ECU and make settings changes on the new ECU. Is that correct?
https://www.ebay.com.au/itm/16-Pin-A....c100677.m4598

3. Any other hints and tips?

Thanks and cheers.

Gally