Hi,

My car has the following fault code P040700 - EGR Sensor "B" Circuit Low.

It started with a flashing glow plug light and then the engine management light came on and engine went into limp mode.

I cleared the fault and it was fine for about 15 miles and then the same thing happened flashing glowplug and the engine management light.

I cleared the fault again and it reappeared almost immediately.

I telephoned a specialist VAG garage and he said that probably the EGR was gummed up and would need replacing.

As anyone else had a similar problem and fixed it? 

Replacing the EGR sounds expensive and is buried behind the engine under the turbo etc. so difficult to get at.

 I would welcome any suggestions.

(By the way I read the fault code using a OBD Eleven device which costs around £40 and is legal.  It is a good bit of kit for the money.)

 

Hi,

Has anyone carried out an institu chemical cleaning of their EGR?  There is a local company that offers the "TerraClean" system. 

Thanks for any replies.

From what I've read, the problems with the EGRs on these engines are not caused by clogging.

Snake oil is not likely to help anything.

In my experience, you need to buy a new EGR, and please save yourself some time and go buy a official EGR from SKODA. These EGR are redesigned several times, and you can not buy a new egr that is not a official EGR from SKODA. I had the same problem, bought  2 different EGR that dont work correctly, ending up buying a official part from skoda that now works great for 20 000KM. Thease parts fail by overheating and they have a electric part on them that fails, and a cooler that starts leaking. The updated original part will hold better over time. 

 

Second option is to blank the EGR and reprogramm ECU by a tuner, which is a bit less expensive, but i heard that people have issues after blanking them out with starting the engine.

 

Good luck and please give us a feedback how you solved the problem.

 

Good luck

Yes, and the last number on the serial number of the EGR is the number of the EGR generation. They have as I can recall over 5 generations(redesignes) of this part. number 1 is the first gen and number 6 or 7 the last updated versions of them. And the new part need to be programmed in the ECU so it could work correctly. 

A local mechanic changed my egr and did not program the damn thing, after 1 day my Octy just cut out while standing at a red light-went to limp mode and couldnt start. A very irritating situation after spending 700euros on the car...

 

Oh, and another info that can help, if you are losing a little bit coolant every few days, it is very likely that it is right on the egr cooler and you need to change the valve (which has a cooler on it attached).

Edited 18 December, 20196 yr by Admir

Hi, Thank you for your reply.  I have had the car fixed by replacing the EGR.  This cost just over £700 at a VAG independent garage and as far as I am aware VAG parts were fitted sourced from TPS.  I kept the old EGR and have taken it apart.  I was surprised how relatively clean the internals were.  All the mechanical side appeared to function OK and the garage said it is normally the electrical part that fails.  This is electric motor (maybe stepper motor) with position sensors i  would guess.  The out put is a plastic gear/cam which drives a poppet valve to open/close exhaust gas flow.  Also there is a vacuum solenoid which operates a butterfly valve.

The valve is quite large see photos below.

In all probability it is the electrical part that fails.  Is this available as a spare?  The part number is 117255.05

Hi, I have attached a couple more photos for interest.

Can you add your mileage? Might be helpful to others to get an idea of how long these are lasting

Yes good point.  The car is now 8 years old and done 110,000 miles.  Which has been a mixture of short journeys and long motorway journeys.

Mine egr was changed at about 210k km, what i heard they can go even from new after just 20k. It depends when was your car built, my octy is from from 2012. 

the german adac was testing thease valves and found that the first few generations had build flows and get stuck which leads to overheating and the electric parts melts.

 

The fact that it even needs it's own heat exchanger on the coolant circuit is a clue that there can be problems with overheating the controller card.

 

Not sure if it is because it is mounted next to the exhaust, or if the controller card itself is making the heat (electronics really can generate some heat!), if it was just an exhaust issue you would have thought they would go back to moving the controller to a cooler part of the engine bay and using a wire or vacuum connection to open and close the valve like previous generations. Maybe the modern type cycle too fast to mount the controller remotely, cable friction or vacuum response time might not be able to keep up?

I thought the cooler was to lower the exhaust gas temperature before it's fed back in to the intake?