EGR Sensor 1 - Signal Too Low - What to do?

[Air_Wolf]

Hi,

For the past week my 1.2, 3 cylinder TDI, has had the EML on. When I hooked it up to VAGCOM the error is;

15536 - EGR Sensor 1
P0405 00 (136 ) - Signal Too Low
MIL ON - Intermittent - Confirmed - Tested since memory clear
Freeze Frame
Fault Status: 0000001
Fault Priority: 2
Fault Frequency: 60
Mileage:91402 km

I posted a thread on VAGCOM forum when it appeared but haven't had a reply, so I thought I would ask this forum thread for help.

I have since bought Wynns EGR Diesel cleaner spray and applied this last night, and I have added a REDEX fuel additive as my thinking was a dirty sensor. I have also read many posts about taking out the EGR and cleaning it. Whilst I could consider this as my next step does anyone think it's a dirty valve with the error that comes up?

The car is otherwise fine, no other issues. I clear the DTC and it comes back after the second outing. I could really use your help before I waste my time on going down the wrong route, or taking dealership advice and replacing the EGR valve and sensors totalling £750.

Thanks

 

[Air_Wolf]

Update - having searched Ross-Tech th ecode above is not found but I have come across this.

Exhaust Gas Recirculation (EGR) Valve Adaptation
Most VW/Audi/Seat/Skoda gasoline engines with Exhaust Gas Recirculation (EGR)

Prerequisites (General):
Ignition ON
Engine OFF
Battery voltage at least 11.5 V

[Select]
[01 - Engine]
[Meas. Blocks - 08]
Select Group 074.
[Go!]
MVB 074.1: Min Position in Volts
MVB 074.2: Max Position in Volts
MVB 074.3: Potentiometer voltage
MVB 074.4: Adaption status: (Run/OK/etc)
[Switch to Basic Settings]
MVB 074.4: Adaption status: (Run) then it should change to (ADP OK)
[Switch to Measuring Blocks]
[Close Controller, Go Back - 06]

Special Notes:
For ECU's using ME 7.5, the coolant temp needs to be between 10 and 50 °C.
In case the adaptation fails switch OFF the Ignition for 30 Seconds, then switch it ON and try again.

What does this do and is it worth trying first?

 

[RUM4MO]

That is just a procedure known as "basic setting" - it is normally only needed to be carried out when you have cleaned the valve or replaced it, what is being done is, the valve gets moved to each of its endstops and these feedback voltages stored for future use, ie the car's ECU will know if these demanded positions are now not being reached.

That procedure will only work for an electrically controlled EGR valve, is your one electrically controlled or does it look like a "flying saucer"?

Edit:- I do not have an experience of modern TDI engines with EGR valves, but it does seem that these valves, in derv engines, do need cleaned out from time to time.

Another Edit:- that quote from RossTech does include the word "gasoline" which, I think, translates into Petrol in our world. (ie all petrol engine EGR valves are solenoid operated)

 

[Air_Wolf]

Thanks for the response. It looks like a flying saucer. Do you think the error code is just sensor related and maybe electrical or should I just strip the valve and clean first?

 

[Fmxvxx]

If you look at the fault code it points to an electrical issue rather than mechanical this is also evident in the fact the car will run correctly until the vehicle completes it's next self check.

When actuated via Vagcom does the EGR valve move? if not Replace EGR

If it does then we have an intermittent issue

I would start by checking power and ground with connector insitu drag test the terminals to check for any signs they are backing out remove and inspect the connector and confirm no moisture in the connector.

At this point I would load test the wires from ECM to EGR but I would recommend skipping this step unless you want to drill the anti tamper cage around the ECM.

If wiring is ok remove and inspect the EGR for sticking valve maybe carbon deposits of moisture present repair/replace as needed.

 

[VeeFource]

I very much doubt it's the sensor that's faulty, it's merely reporting the mechanism is jamming due to being sooted up and as such is not moving to it's required positions. The car can only see it as a discrepancy between what it's telling the servo to do and what the position sensor is saying it's actually doing. You can try a fuel additive and avoiding supermarket fuel to help free up the mechanism but it's a long shot and if it doesn't resolve itself it's new EGR valve time I'm afraid.