Passat 1.6 TDI p0407

**Crasher** · 25-06-2021,03:57 PM

What fault codes are you getting?

**Patters1978** · 25-06-2021,04:23 PM

At the start just 0407 but that goes away once it has been started a few times

**Crasher** · 25-06-2021,05:09 PM

I did warn you over aftermarket EGR valves, that is exactly what happened to me on a Golf 6 about five years ago.

**Patters1978** · 25-06-2021,06:12 PM

Originally Posted by Crasher

I did warn you over aftermarket EGR valves, that is exactly what happened to me on a Golf 6 about five years ago.

How can I completely bypass the EGR for testing to see if car idles better? I thought I'd be safe with borgwarner

**Crasher** · 25-06-2021,10:35 PM

You must know me by now and my obsession with emissions, I don’t know how to bypass these valves as I refuse to get involved with it.

**philipharmes** · 26-06-2021,09:40 AM

The one thing I have noticed today is a funny smell coming from the car which is hard to describe.. it's like gas or electrical smell

I would check around where all the work has been done for gas leaks.
Look all around the back of the engine in the dark with a torch.
You should see any gas leaks.
Do it from a cold engine start.

**Crasher** · 26-06-2021,02:33 PM

If you disconnected the DPF (you have to really) did you use a new turbo gasket and clamp? These are notorious for not liking to being reused.

**Roverfan** · 28-06-2021,11:56 AM

I think you may have more then one fault, the passat ecu's (not usually on 1.6) do have issues though which i have come across on here. Im not saying its the ecu but its possibility for a single cause of these faults

For P0407 fault diagnosis, i'd monitor the egr wiring. It should be a 5 wire system. You have a thicker power and ground for the motor. Three wires for the position sensor. A shared 5v and a shared ground, and signal wire back to the ecu. The 5v power and ground in particular needs monitoring to see if it drops out since its shared and that naturally carries higher chance of something dropping out.
If no problems with the 5v wires the signal wire checking to see what voltage the egr is outputing and what voltage is reaching the ecu.

Easier said than done but this needs checking for clarity as to whats causing the fault code

**Patters1978** · 28-06-2021,03:13 PM

I'll shall try and check some of these things mentioned.
What I don't get is it only happens on the first couple of starts after that the car drives fine with no hiccups? If it's drove with the error it's into limp mode.
I have drove it for 50 miles to see if that changes anything (ecu learning) but no.. next day start the car error comes up leave it for 1 min idling and it's good to go after a restart.

**Patters1978** · 28-06-2021,03:17 PM

The other thing I will be trying is swapping over the motor part from my "VW" egr to the "borgwarner" egr if they are indeed fussy I wonder if it's within the electronics of the motor rather than any mechanical part of the EGR.
My "VW" motor does not have any stripping of the plastic so should be fine to change and hopefully not a pain to do