Emissions Workshop! - EGR Insufficient Flow?

[iCraig]

Hi All,

Currently my 2005 Octavia 1.9TDi (BKC) has come up with the CEL Light on and saying Emissions Workshop! on the Maxidot.

I had it scanned by a local vag specialist and they've said the fault thats coming up is EGR insufficient flow. So I've had the EGR cleaned out and tested, the light reset but its come back on again.

Has anyone ever had this before? As I did a search and it doesn't seem a hugely common problem? If so how did you rectify it and what exactly was wrong?

Thanks in advance,

Craig

[xpower]

I believe that the EGR 'flow' (in your case insufficient) is calculated by looking at the engine speed, throttle position/engine load, and air flow (calculated by the MAF)

Basically when the EGR is open there is less OUTSIDE air coming in resulting in the MAF reading a lower airflow.

If the ECU opens the EGR (the electrical command is sent) but the MAF still reads consistently high the ECU pressumes the EGR is faulty (not opening enough) and flags up the fault code which you have.

OBD code P0401 - EGR insufficient flow detected

Possibilites, but not limited to:

1. The new EGR is faulty

2. The vacuum pipe from the EGR to the EGR valve control solenoid is split or broken - failing to open the EGR

3. The vacuum pipe from the EGR to the EGR valve control solenoid is blocked / gunged up - failing to open the EGR

3. The MAF is reading incorrectly

4. There is a wiring issue to the EGR valve solenoid

5. The ECM / ECU is faulty

If this was my job then I would start by checking for wiring faults, I would then check if the ECU is sending the command to the EGR solenoid (using a multimeter or oscilloscope) and attaching a vacuum gauge to the EGR valve itself.

Don't you just love diagnostic jobs :-D

Good luck

[iCraig]

The mechanic that cleaned the EGR said it was full of of oily carbon deposits. So would the vacuum pipes require replacing if they're gunged up too?

Really beginning to hate this car though, its currently costing a fortune and its only done 114k!

[xpower]

TBH my golf 130 PD's EGR was also full of gunk when I cleaned it a few weeks back (done 115k ish)

Is the mechanic at a loss as to what is wrong or is it a matter of £££'s?

If the physical EGR was so gunked up it would not shut correctly then I would have expected a fault code with excessive flow not insufficient.

[iCraig]

TBH my golf 130 PD's EGR was also full of gunk when I cleaned it a few weeks back (done 115k ish)

Is the mechanic at a loss as to what is wrong or is it a matter of £££'s?

If the physical EGR was so gunked up it would not shut correctly then I would have expected a fault code with excessive flow not insufficient.

No he says I need a new EGR now thats not worked, although a lot of searches say other things can be wrong but it'll say insufficient flow on the fault code?