Touran tdi dpf sensor nightmare

[ryanp29]

Hi, I've got a touran 2.0 tdi 170 bmn, it's currently stuck in limp mode, it started with the dpf light coming on, so as soon as I could I took it on the motorway for a blast, however as I got to a suitable engine speed, I put the cruise control on and a few seconds later the coil light and EML came on and she went into limp mode, next day a mates code reader came up with - 08194 particulate trap bank 1 below efficiency threshold P2002 short with power, so then I took it to a garage to confirm the code and get a professional opinion and as I first thought, he thought the same - dpf pressure sensor, fitted a new one and now I still get the same code, he tried taking it for a drive and performing a regen, but it's still the same! He then suggested a short or damaged wires, I've checked the wires and after a few resistance checks they all appear fine, however I've still got the same problem. Although if I disconnect the dpf pressure sensor, the coil light disappears and the car drives normally??? With the EML and dpf light still on?
Anyone got any ideas? It will be very much appreciated



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[Flash2]

Anyone got any ideas? It will be very much appreciated
Did the guy in the garage confirm the correct voltages were present at the sensor? With the sensor connected and the ignition on, use a pin/needle to back probe each wire on the sensor connector and measure the voltage on the wire. You should have one with 5V (power supply), one with 0.5V (signal to ECU) and one with < 200mV (earth). Once you've confirmed that's correct connect the meter to the signal wire again and start the engine. The signal voltage shouldn't change by much when the engine is started...if the particulate trap is clear.

I found this video on youtube showing DPF sensor voltage measurements before & after a regen :


http://www.youtube.com/watch?v=YlZMRdeiT-8

[ryanp29]

No mate he never tried this, but I will tonight after I get home from work.
Many thanks for your help with this.


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[Crasher]

18434 (P2002) 008194 - Particle Filter Bank 1: MalfunctionThere is no suggestion of a wiring fault or problem with the sensor, you only have one code. You need to use advanced measuring blocks to see what the Ash Mass figure is, if it is above 60g the DPF will need either cleaning or replacing. Cleaning allows you to reduce the ash mass figure to 50% of maximum, not 0.

[ryanp29]

Hi Crasher, I'm not sure but I think because the code reader said short with power, as well as particulate trap below efficiency threshold and that he replaced the pressure sensor and the same fault came up afterwards and he attempted to delete the fault code unsuccessfully, is why he suggested a wiring fault??


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[Crasher]

So there is another code?

[ryanp29]

Only codes are p2002 and 01894


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[ryanp29]

Only codes are p2002 and 01894


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[Crasher]

18434 (P2002) 008194 - Particle Filter Bank 1: Malfunction

P2002 and 01894 are the same code as is 18434, just different standards and there is no wiring issue hinted at and it is not the EGT sensor...

18434/P2002/008194 - Ross-Tech Wiki (http://wiki.ross-tech.com/wiki/index.php/18434/P2002/008194)

[ryanp29]

Thanks, he did say that the sensor was not giving any load readings, although he did replace it with a genuine one from VW and managed to do a regen whilst driving with his kit connected to the obd ,could a blocked dpf be the cause? The code reader did say short with power, I thought that could mean a electrical issue?


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[Flash2]

could a blocked dpf be the cause......I thought that could mean a electrical issue
The voltage test I suggested earlier only takes 5 mins or so and should give you a good clue about whether it's an electrical issue or a blockage. A short to power would make the ECU think the filter was blocked when it's not since the sensor output voltage is proportional to exhaust back pressure. If the wiring is shorted though, you wouldn't get 0.5V before the engine is started. The voltage would likely be higher than that. Having said that, a higher voltage key on/engine off "should" cause the ECU to log a sensor plausibility code which you don't have. But fault diagnosis is all about collecting clues about the fault and if I can collect another clue at the expense of 5mins work I think that's 5 mins well spent.

[Crasher]

Did he recalibrate the sensor to the ECU?

[ryanp29]

No, after reading up on the forums I heard about this I think some call it adaptation? I ask him if he needs to do this whilst he was trying to fault find but he told me that he needs to get load readings first, do you think that could be the issue?


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[Crasher]

A new sensor must be calibrated.

[ryanp29]

Hi I've carried out the voltage check and got the following results- yellow/ blue wire 5v, purple/ green wire 0.5 v, upon starting engine I got the same results apart from the signal wire increased to 0.6v when the engine speed was increased, so am I right in saying that the wiring is ok and the dpf is clear??


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[ryanp29]

Hi all, just had it code read again and now the code is 01139 exhaust pressure sensor 1 (g450) signal to high p0473 short with power??? Any ideas guys??


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[Crasher]

You caused that by unplugging it with the ignition on, you can't do diagnostics with a multimeter unless you have a code reader to clear the codes afterwards, otherwise you chase your tail around in circles.

[ryanp29]

It went to the garage after I checked it all out with a multimeter to have the codes erased but it would not let him clear it! https://uploads.tapatalk-cdn.com/20170515/0bfbf6b09c1bab627f1b6f83a210802b.jpg


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[Crasher]

If the sensor is new the wiring back to the ECU needs checking. Firstly, there is a fourteen pin connector near the battery where the G450 wires pass through

G450 T14

1. Yellow/blue at pin 11
2. Grey at pin 4
3. Lilac/green at pin 3

Check at this plug for corrosion or damage first.