Engine Management System light problem

[Dippy]

My EMS light came on, with no other warnings. But when I tried to check DTCs with VAG-COM, it wouldn't connect (com port OK, but host not found).

Anyone else had this problem before or have any ideas?

I guess I could try disconnecting the ECU, just to see if I can then connect to other modules with VAG-COM.

Alternatively I could try resetting the ECU. Presumably that can only be done by disconnecting the battery?

[PetrolDave]

(com port OK, but host not found).

Just checking that you had the ignition turned on? That's the most common reason for that error message.

Can you connect to any other controllers, e.g. address 1 (engine ECU),

[Dippy]

Thanks Dave. I think it was a laptop problem. I updated my VCDS and USB driver and tried again with complete success. It turns out the that fault is an old fault I inherited when my Miltek exhaust was fitted (I believe it runs a bit too cooler than standard so a temperature is sometimes below threshold). The only mystery is why in the past several years it is the first time (as far as I know) that it has invoked my EMS light. Normally I just notice it when checking DTCs and clear it.