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Discussion Starter #1
***Exhaust pressure sensor fault fixed***

This may save you £80+ for a new Exhaust pressure sensor should your engine light come on with this fault code.
Mine kept coming on and in due course I switched it off via my code reader only to have it come back on a few days later.
So, with nothing to loose I took off the sensor shown below. its located above the engine on my T5 2.5;
(remove the two pipes, disconnect the plug and undo the spline screw)



Use a spare piece of flexipipe to blow down the two pipes. This will identify any blockage issue you may have in the pipes. There should be no resistance and air should pass through them freely (well, mine did).

Right, onto the sensor. Take it indoors and allow to warm to room temperature. Hold it with the two pipe connectors upwards and fill with Electrical contact cleaner shown below;



Allow to stand for 1 hour. Empty out and allow to drain for 1 hour. Repeat the last step using good old UB40 spray lubricant (there's a song in there somewhere) Fill 1 hour, drain 1 hour.
Carefully blow through with Compressed air aerosol;



Re-fit sensor and reconnect plug giving it a squirt of the Electrical cleaner.

This worked for me, the next day the engine light on the dash went off by its self and has been off for weeks now.

++++I don’t know what’s inside the sensor or how it works so if you damage yours trying I take no responsibility.+++++

It worked for me and hopefully it will save lots of people an unnecessary ‘main stealer’ bill (which we can all do without).

Happy Dubbin folks.:ILU::ILU::ILU:
 

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I sincerely hope you have fixed the sensor, but this device measures quite a small diffential air pressure and is a sensitive device.

The only way to be sure it is working OK is by knowing what the voltage output should be with zero diffential pressure (both pipes open to atmosphere) and what it should be at a point where the fault light is triggered? I guess VW don't give-out this information as they want the dealers to sell you a new one (and most techs are not trained to repair stuff anyway these days).

I hope your DPF doesn't explode because it really is blocked but the sensor is fooked! T:
 

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Discussion Starter #3
I sincerely hope you have fixed the sensor, but this device measures quite a small diffential air pressure and is a sensitive device.

The only way to be sure it is working OK is by knowing what the voltage output should be with zero diffential pressure (both pipes open to atmosphere) and what it should be at a point where the fault light is triggered? I guess VW don't give-out this information as they want the dealers to sell you a new one (and most techs are not trained to repair stuff anyway these days).

I hope your DPF doesn't explode because it really is blocked but the sensor is fooked! T:
Well I hope so too, thanks for that but if there is a problem with the sensor then I'm guessing the light would still be on......
 

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My concern with the repair is that you may have damaged the sensor, inside the sensor is a piezo crystal that creates a small voltage when pressure is applied to it (works the same way as an engine knock sensor) the reason these early type fail ( there is a modified sensor available) is they get moisture in from the DPF pipes this then changes the pressure in the sensor causing false readings. To introduce moisture and then blowing into it could damage it internally to the point where it doesn't recognise a difference in pressure either side of the DPF so no light on. Hopefully this hasn't happened but would perhaps check by swapping sensors with someone else and compare the pressure readings using measure blocks in vcds, better to be safe than £1000+ for new DPF
 

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Discussion Starter #5
Thanks for your concerns.
For the record and in case there is any confusion, the warning light I mentioned is NOT the DPF light, it is the orange engine light which indicated a fault with the DPF/pressure Sensor unit and NOT a fault with the DPF itself.


Unless I am mistaken I would expect that if the sensor is not operating correctly, the ECU will display the sensor fault light?
If it is operating correctly (no engine light) and there is an issue with the differential pressure then the ECU would display the DPF light and perform a Re-gen?

If anyone knows for sure why this is not the case or has any helpful facts to share I/we would appreciate hearing them.

My theory was; the electrical contact cleaner would clean any electrical contacts inside the sensor, the WD40 would lube any moving parts and disperse any moisture (like dampstart in a distributor cap) and the air would remove any excess WD40.

NB, When I said “Carefully blow through with Compressed air aerosol” I MEAN carefully blow through, NOT blast through like a sand storm......

Hopefully someone will know for sure?
Thanks.T:
 

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I had a faulty dpf sensor that showed not warning lights.
My van cut out after losing power and juddering loads.
I took it to my vag mechanic his tester said dpf sensor fault and misfire cylinder 5
New dpf sensor fitted now running worse than ever. Taking van back to get it checked.
Dosnt like traffic jams tries to stall.
Checked turbo and that's leaking badly on exhaust side.
No dpf warning lights ?
 

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Discussion Starter #7
I had a faulty dpf sensor that showed not warning lights.
My van cut out after losing power and juddering loads.
I took it to my vag mechanic his tester said dpf sensor fault and misfire cylinder 5
New dpf sensor fitted now running worse than ever. Taking van back to get it checked.
Dosnt like traffic jams tries to stall.
Checked turbo and that's leaking badly on exhaust side.
No dpf warning lights ?

Its probably nothing to do with the sensor then......
 

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No dpf warning lights ?
As I understand it, the DPF warning light is used for only one purpose - to indicate that the DPF is blocked and needs a specific driving pattern to allow regeneration to start.

A faulty DPF sensor should log fault codes in the ECU, and may cause one of the engine management fault lights to come on (either the engine symbol or the flashing glow plug light) - it should not cause the DPF warning light to come on.
 

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Discussion Starter #9
As I understand it, the DPF warning light is used for only one purpose - to indicate that the DPF is blocked and needs a specific driving pattern to allow regeneration to start.

A faulty DPF sensor should log fault codes in the ECU, and may cause one of the engine management fault lights to come on (either the engine symbol or the flashing glow plug light) - it should not cause the DPF warning light to come on.


Hi Traffic, That's what I figured, so, if I have damaged the sensor by cleaning it out then the fault light would still be on? The light isn't still on, it switched itself off after I cleaned the sensor as explained above so as far as I can see there is no longer a problem?

Have I found a fix for this common sensor fault or will I explode like a SCUD as Mr TT62 suggested?.
What do you think and does everyone agree?



Cheers.
 

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The ECU is obviously "happy" with the signal (voltage output) coming from the sensor (assuming it has switched itself off after you "fettled" it)?

I hope its working okay, but this may not be the case! It might just be that it no longer responds to a pressure differential, but just happens to be giving a constant voltage output to the ECU which corresponds to a "good" or "normal" signal...........who knows without testing it?
 

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I had a faulty dpf sensor that showed not warning lights.
My van cut out after losing power and juddering loads.
I took it to my vag mechanic his tester said dpf sensor fault and misfire cylinder 5
New dpf sensor fitted now running worse than ever. Taking van back to get it checked.
Dosnt like traffic jams tries to stall.
Checked turbo and that's leaking badly on exhaust side.
No dpf warning lights ?
Vans back with garage, they put their tester on it, it found no faults errors, no mis fires.
Mechanic took it out for a test drive, I told him it dosnt like low revs around 1800rpm or less, it judders a bit, very hesitant when you put foot back on throttle and seems to lack power. This is an auto box not sure if this will have anything to do with it.
I had no warning lights on my dash when the dpf sensor was faulty.
 

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Discussion Starter #12
Well, 4 months on and a fair few miles gained and still no problems, no warning light and I haven't blown up T:
 

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We had the light on a while ago with the code relating to the pressure sensor. I cleared it with my reader and it's been fine for a while.

Tonight the lights come back on, I haven't scanned it yet but assume it's the same thing again.

I did notice the van revs fluctuating while sitting on the motorway. Rev counter showed it dropping 100 or so rpm while sitting at 3k rpm with the cruise on and could feel a bit of a judder. Parked up, started van an hour or so later and the light came on.

I wonder if mine is worse than just the sensor as both times it's come on I've noticed the engine doing something unusual, last time it felt like a misfire at low revs.
 
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