DPF differential pressure sensor dead at 60,000kms

[Greg Roles]

Hi Guys,

Have been noticing my DPF regens becoming more and more frequent, and normal Vag Com scans showed no errors or any odd readings. I've done some in depth testing live with a DPF app and my OBD dongle and it turns out my DPF pressure sensor works perfectly at urban speeds, but the second I hit 100kph, it freaks out, the DPF goes from partially to totally full, and the car is trying to regen the entire time I am at speed. Gotta love that endlessly dodgey DPF sensor.

Anyway a new one is on the way, but just wanted to warn people to be vigilant, this car is only a year and a half old, and whilst higher kms than most, you would expect the new "B" revision sensor to last a little longer. So if your newer diesel is using a bit of fuel, or you notice the radiator fans on a bit more than usual when you pull up, my vote is that god damn sensor is playing up, and you will need a new one. Hate to think what the last few weeks have been doing to my oil, so gonna drop and replace it as it;s no doubt full of diesel from the late injection.

We need an aftermarket billet DPF pressure sensor!

[Transporter]

Greg, there is no "B" revision sensor. The "B" means you're looking at the DPF sensor for usually 4 cyl. VAG engines, which has the voltage output approx. 1V at 0 pressure. The DPF sensor which p/n ends with the letter "A" has the output voltage 0.5 at 0 pressure.

There is an aftermarket sensor from BOSCH for your Yeti, which I use instead of the genuine one, it fits all VAG 4 cyl. TDIs.

[Greg Roles]

Sweet, great info Miro, screw the OEM Malaysian one....

EDIT: Man, there's a ton of China copies out there now, beware people, Miro I can only find the Bosch "A" OEM spec one.

[Greg Roles]

Well until I find the right Bosch part as Miro so kindly pointed out above, I have simply disconnected my dud pressure sensor, the car has defaulted to km based DPF regens, and the car is operating properly again, I'm 300kms in and the DPF is filling normally, and I expect a regen at 400-500kms as usual. Hooray! Funny that a light on the dash and an unplugged sensor is far better than the plugged in option.

[gldgti]

Explain something to me Greg (or Miro)
Greg, you keep saying differential pressure sensor... Are you saying there is 1 sensor connected to 2 locations (inlet and outlet) and it shows a voltage based on the difference?

interesting what you described in the first post too - sounds like it must just not like the 'large differential' readings.

[Greg Roles]

Yep spot on.

The DPF sensor measures the pressure difference across the DPF core, so one pipe from the front of the DPF and one pipe from the back of the DPF, with a small membrane sensor between the two. As the pressure builds pre DPF due to soot clog, the membrane moves and a voltage changes. If you look at a DPF you will see exterior metal pipes about 4mm thick, these carry the pressure to the sensor.

[Transporter]

Explain something to me Greg (or Miro)


interesting what you described in the first post too - sounds like it must just not like the 'large differential' readings.

or
1. the sensor itself is faulty
2. fault in the wiring or the leak in the connecting hoses

the output voltage of the sensor can be checked with the fast oscilloscope or the graphing voltmeter.

[saint70]

Greg, there is no "B" revision sensor. The "B" means you're looking at the DPF sensor for usually 4 cyl. VAG engines, which has the voltage output approx. 1V at 0 pressure. The DPF sensor which p/n ends with the letter "A" has the output voltage 0.5 at 0 pressure.

There is an aftermarket sensor from BOSCH for your Yeti, which I use instead of the genuine one, it fits all VAG 4 cyl. TDIs.

What would be normal regen cycles? Now i am getting every 1000 km regen....no dash light, just rpm increase a bit and cat losing speed...
Regards

Sent from my D6503 using Tapatalk

[Bora Sport]

Just a question here which hopefully doesn't sound too dumb. How do you know when a regen is occurring. I assume our 125 TDI 2010 Jetta has a dpf. It has done 229,000k's and I've never had any sensation that anything was happening. I have however noticed that the oil never seems to need topping up. Typically fuel consumption is around 5.3 at highway speeds with the aircon on and maybe 4.8 without the air on.

[Greg Roles]

Saint, a regen every 1000kms is legendary, I'd hazard a guess you are actually missing the 500km one, I've always had 400-500km regens in the MKV GT TDI from new, and the MK6 era CR Yeti from new, on stock tunes.

Bora the MK6 CR era engines have a very unobtrusive regen, you can't feel it at all unlike in the PD MKV's, and all I can notice is a slightly deeper exhaust note below 1500rms, and a hot tail pipe. If you stop somewhere mid regen the fans will keep running for a time, but other than that they are very hidden.

Miro, all good things to check, actually the pipe leak may be my issue as only at higher exhaust pressures from highway speed does it freak out, but it's odd a 0-100 sprint doesn't set it off, seems more speed dependant!