My little Fabia has thrown the occasional amber caution light "control system for exhaust" (the one shaped like an engine.  The first, about 3 years ago was sorted with a new coil.  The second occurred during the snows of last year and cleared without any further action. 

 

Today was dramatically different.  With the engine up to temperature, but after a downpour, the light came on and the car entered the limp mode.  After turning off for about 10 minutes the car restarted without the lamp and all was well for about 15 minutes.  Then the same occurred.  After waiting an hour the car managed a further 60 miles but the caution light remained on. OK, I was probably pushing my luck but the car was running well except for the light.  Suddenly the engine cut out completely.  When I pulled over the engine would turn over on the starter but their was no sign of starting.  When the recovery man arrived the fault light had cleared but the car still did not show any sign of wanting to fire up and the diagnostic kit could not achieve a connection with the engine system.  The recovery man did say that the car was turning over quickly and that low compression may be an issue. 

 

Connecting my own scanner this evening confirms no link to the engine system but I get the following codes through the ABS and central electrical system:  01314 and 18265.  Both indicate comms problems with the ECU.

 

Given the linkages between all these systems I do not want to jump straight to a faulty ECU and would be grateful for any further diagnostic advice that I can do with only normal tools and a fairly simple VAG scanner.  

Coilpack has prob failed, they sometimes short and blow the fuse for the ecu, check each coilpack for burnt smell or disconnect all of them then replace the fuse to see which one is faulty

Can't remember which fuse now so check every one

Fuse No.10 of the ones on top of the battery looks like a candidate, according to pages 188/189 of the Owner's Manual. May well be some relevant ones in the cabin fusebox too, but I thought I'd just mention the battery compartment ones as not everyone knows they're there.

Thank you for the guidance.  It has turned out to be the No1 coli pack and the ignition fuse had blown.  Just need to repair the burnt connector before fitting the new coil pack.  Annoying but relieved that I don't have to face an ECU problem (hopefully).  Thanks again.