My Fabia 16v Saloon has been showing a number of minor faults on VAG Com scans - some of them have been there years. I've come to the conclusion that either the garage doesn't do a diagnostic when it goes in for service or can't be fagged to clear the codes.

Anyway, a rather more serious fault has been indicated in the last week (EGR - excessive flow), with the EM light being illuminated. I have a strong suspicion that this may be a spurious report - I recently had to change the battery. Also a fault has just appeared with the Airbag electrics, which I have been advised definitely arises when the battery is disturtbed.

Therefore want to clear the fault codes to determine if it the EGR fault is genuine.

How do you do this using VAG Com and can faults codes be cleared selectively ?

Nick,

16/07/07

,

I don't think you can clear individual codes, but you can clear them by channel.

When you do a fault code scan, when it finishes just press the button at the bottom that says clear codes.

The VAG-COM User's Manual notes that there is no way to erase individual DTCs while leaving others alone. This is not a limitation of VAG-COM, but is the way VAG protocols work.

Look at it this way: If you clear code(s) for a fault that still exists, those codes will be back soon enough..;-)

-Uwe-

You can however clear code by individual controller by opening that controller and choosing fault codes and then clear fault codes.

As Uwe says, it'll do no harm to clear them - They'll soon be back if you've got a problem. Might be worth keeping a record of what they are though.

Well I did a scan this evening and this still showed the EGR and some other modules with a problem. The EM light is still on with the Engine running.

After the first scan, I DTC'd the codes and the scan that automatically starts after this still showed the EGR had a problem, although a lot of the other fault codes disappeared.

Took it up the motorway 15 miles round trip and, on return home, gave the valve several light taps with a pin hammer - the usual trick to free a mechanically jammed solenoid. Started engine, EM light still on.

Outside case of valve and surrounding area looks remarkably free of dirt

I presume that this indicates that there is an electrical fault with the EGR and and that it will have to be replaced.

The car seems have lost the misfire which it first had when the EM light came on a week ago. Could this be the EMU compensating for the failed component or do these valve's exhibit partial and intermittment faults ?

The car seems to have more "uumph" and torque especially just below 2000 revs - usually a dead zone. Has the valve failed in the open position but the electronics are telling the EMU it is closed, so the EMU is richening the mixture ?

Anybody know how much one of these costs and whether it can be replaced by the home mechanic ?

I attach the "Before" and "After" scans.

Nick,

16/07/07

These are very common - The search will answer your questons -

3 Faults Found:

01596 - Motor for Outside/Recirculated Air Flap (V154)

30-10 - Open or Short to Plus - Intermittent

01596 - Motor for Outside/Recirculated Air Flap (V154)

29-10 - Short to Ground - Intermittent

01596 - Motor for Outside/Recirculated Air Flap (V154)

28-10 - Short to Plus - Intermittent

Often seen when the battery is removed -

01598 - Drive Battery Voltage

07-10 - Signal too Low - Intermittent

The postscript to this story occured this evening.

I visted my local dealer, who reset the codes and put -out the EM light - something I'd failed to do with VAG - Com. Interestingly, he used a hand portable box of tricks, with a simple one or two line digital display, to do this. Any way it worked - stronger signal than the USB/Can connector on my laptop ? Or do you have to run the DTC process on VAG - COM twice, first to clear the fault codes and a second pass to put out the EM light ? In the event, I only ran it once and the EM light stayed on, even though the fault code cleared.

I was told that it was an intermittment fault (I presume the instrument revealed this), probably caused by mechanical or electrical issues - the throttle body was inspected and found to be clear of excess oil and sludge, thereby discounting the other major cause of problems. The advice was to continue driving the car as normal, and, that, if the light came on again the replacement of the valve should be considered.

Apparently, this is not a job for the home mechanic as a software accomodation of the new part has to be made - presumably under the control of workshop equipment . Shame, cos the a replacement valve is only

Sounds like he was using VAG 1552 diagnostic machine, well behind the capabilities of VAG COM and has been out of date for a good 5 years at least now. But older dealers who still have one sometimes keep them for clearing service lights etc, however they cant be used on the newer cars and ar really now all but defunct.

Could well be a faulty EGR valve, might also be worth checking if the engine ECU is running the latest software, therehave been a few changes to some ECUs to broaden the parameters to stop the light coming on.

I visted my local dealer, who reset the codes and put -out the EM light - something I'd failed to do with VAG - Com. Interestingly, he used a hand portable box of tricks, with a simple one or two line digital display, to do this. Any way it worked - stronger signal than the USB/Can connector on my laptop ?

No, you've got a bunch of this in your scans:

No Faults Found

or DTCs not supported by controller

or a communication error occurred

That mean you've got some dodgy communications happening. You need to go here.

Apparently, this is not a job for the home mechanic as a software accomodation of the new part has to be made - presumably under the control of workshop equipment . Shame, cos the a replacement valve is only