Bazz - is the ECU fault a failed driver for the motorised throttle? As in, bin the computer time? What actually causes it?
This is a fault that usually occurs on any of the engine ECUs that are mounted onto top of the Throttle bodies, 156TS, 156GTA, 147TS, 147GTA. It is not as prevalent in the JTS cars.
The problem is a manufacturing defect where one of the main surface mount power capacitors develops a crack in one/both of the solder joints or breaks loose completely.
As long as part of the circuit board does not break away as well and your are Professionally trained in Micro Miniature Surface Mount repair and reworking and you have the right equipment it can be resoldered.
But you have to understand, you are working in areas where thin gold wires 1/10 the thickness of a hair are soldered all over the place, and all the circuitry is covered in a thick layer of non conductive gel!
So, if your cool with all that, go knock yourself out and all the luck to you.
The usual procedure is to toss the ECU and get a replacement set from wreakers of the following
156: Eng ECU - Immobiliser Box/ECU - Key Immob chip
147: Eng ECU - Body Computer - Key Immob Chip