Here we go then:

VAG-COM Version: Release 311.2-N

6 Faults Found:

16684 - Random/Multiple Cylinder Misfire Detected

P0300 - 35-10 - - - Intermittent

16685 - Cylinder 1 Misfire Detected

P0301 - 35-10 - - - Intermittent

16687 - Cylinder 3 Misfire Detected

P0303 - 35-10 - - - Intermittent

16891 - Idle Control System RPM Higher than Expected.

P0507 - 35-10 - - - Intermittent

17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)

P1297 - 35-00 - -

17544 - Fuel Trim: Bank 1 (Add): System too Lean

P1136 - 35-00 - -

All this is accompanied by the sound of air escaping from the front of the engine, towards the battery end. Wiggling the hoses gives no clues to what is going on and you cant "tune" the hiss by moving anything.

I'l swapping the DV for a standard item this evening to see if that helps at all - any other ideas?

Seems I may have split hose, from reading this:

http://www.briskoda.net/forums/octavia/7798-fault-codes-17705-17545-a.html?highlight=17705

It is possible that I have a failed coil pack (or 2) though this is doubtful as I would have expected them to fail before now (92000 miles)

Do I get a prize for the first person to post about 16891 and 17544 though ?

Have you checked the problematic bottom hose? There is a modified part if you do need to replace it. You could try swapping coil packs on Nos 1 and 2 cylinders then scanning again after a reasonable run to see if the misfire has followed the coil pack. They aren't all that expensive to change - circa

Strangely, the car was running fine until I fitted the ebay CAI. That was on for 1 day before I got fed up of the noise.

The poor running started a week after the standard airbox was refitted and a few hours after using Tesco 99 RON. Probably no connection what so ever.

Throttle body has been reset twice since then and its had 2 tanks of shell 95 RON through it since.

Both of these things could be just a coincidence but we'll see.

6 Faults Found:

16684 - Random/Multiple Cylinder Misfire Detected

P0300 - 35-10 - - - Intermittent Tied in with below

16685 - Cylinder 1 Misfire Detected

P0301 - 35-10 - - - Intermittent Sounds like a coil pack' date=' what prefix do you have?[/color']

16687 - Cylinder 3 Misfire Detected

P0303 - 35-10 - - - Intermittent As above

16891 - Idle Control System RPM Higher than Expected.

P0507 - 35-10 - - - Intermittent Never seen that before tbh, but wil probably clear when others are sorted

17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)

P1297 - 35-00 - - Common one, check boost pipes/DV/Clean and reset throttle body

17544 - Fuel Trim: Bank 1 (Add): System too Lean

P1136 - 35-00 - - Probably related to above, could be fault MAF

Probably not a good idea to post your chassis number and you immobilizer serial number on a public forum.

Thanks, Ross. Information removed

Will SKoda replace coil packs FOC on an out of warranty car?

You will have to contact your dealer. Each case is now submitted for prior approval by warranty.