HELP Exhaust Pressure Sensor 1 (G450): Signal too High

[jazd]

Drove home from work (about 50km highway driving) and car started feeling a bit funny last 10km or so, felt less powerful and was holding gears at higher revs than normal (about 500rpm higher).

Anyway started car up about 2 hours after I got home to go out and engine light stayed on. Drove similar to how it was in the last 10km home from work. Only drove it a couple of km then turned it off again.

Put the VCDS on it and this is what it came up with -

Monday,29,August,2011,21:37:30:27769

VCDS Version: Release 10.6.4

Data version: 20110418







--------------------------------------------------------------------------------

--------------------------------------------------------------------------------





                Address 01: Engine       Labels: Redir Fail!

Control Module Part Number: 03G 906 018 FC    HW: 03G 906 018 FC

  Component and/or Version: R4 2.0l PPD1.2 G    4357

           Software Coding: 0000078

            Work Shop Code: WSC 06441 785 00200

                      VCID: 6BFB151C3315

1 Fault Found:



001139 - Exhaust Pressure Sensor 1 (G450): Signal too High 

               P0473 - 006 - Short to Plus - MIL ON

             Freeze Frame:

                    Fault Status: 11100001

                    Fault Priority: 1

                    Fault Frequency: 120

                    Reset counter: 40

                    Mileage: 101333 km

                    Time Indication: 0

                    Date: 2000.00.00

                    Time: 10:45:10



             Freeze Frame:

                    RPM: 832 /min

                    Torque: 40.0 Nm

                    Speed: 0.0 km/h

                    Voltage: 10.96 V

                    Mileage: 0 km

                    Text:   84    C               

                    Pressure: 1001.1 mbar





Readiness: N/A

Anyone know where the exhaust pressure sensor is at so I can check it out. Any other ideas?

[jazd]

Going to answer my own question now.. minutes after posting. Turns out Googling found me an answer pretty quick.

The G450 sensor is the DPF pressure differential sensor and apparently it fails pretty regularly on the PD 170 engines.

Funny thing is the VW self study gives the following symptoms if it fails, which isn't what I experienced.

In the event of signal failure from the exhaust gas pressure sensor, the particulate filter regeneration cycle will be based on the distance travelled or the number of hours in operation. This cycle for particulate filter regeneration, however, is not effective over a long period of time. After a predetermined number of cycles, the diesel particulate filter warning lamp will light up and the preglow control lamp will then flash in the dash panel insert. This informs the driver that the vehicle must be driven to a workshop.

But aside from the different warning lights, the behaviour of the engine is reasonably explained if the pressure sensor is bust.

I would reckon it would be pretty safe to drive but I might try and fix it in the morning. Lucky I have a VW spare parts department within easy walking distance.

BTW, this pretty much settles it. The DPF is coming out at some point, hopefully soon,

[jazd]

Can anyone confirm that this forced regeneration procedure is required to adapt the ECU to the new sensor after replacing -
Diesel Particle Filter Emergency Regeneration - Ross-Tech Wiki

[Greg Roles]

Hi mate, yep I have had the same failure, and the replacement part is apparently an upgrade, but despite trying that forced regen and quite a few things actually my DPF regens have been on milage ever since, and this was back when the engine was still relatively stock. I've no chance of getting back to "normal" regens now, but I'd be having a long chat with VW as to how exactly you adapt the new sensor, for I wasn't able to get it to work as the old one had, which is rather odd, but like you the stock DPF days were numbered so I didn't dwell on it.

Hope to have options on the DPF soon, just need to prove it will work....

[gldgti]

mate - if the reading is too high, this is not necessarily the same logic that applies if the sensor has failed. sounds like your car was trying to regenerate the dpf anyway.

you havent tried going for a long highway drive?

[jazd]

Hi mate, yep I have had the same failure, and the replacement part is apparently an upgrade, but despite trying that forced regen and quite a few things actually my DPF regens have been on milage ever since, and this was back when the engine was still relatively stock. I've no chance of getting back to "normal" regens now, but I'd be having a long chat with VW as to how exactly you adapt the new sensor, for I wasn't able to get it to work as the old one had, which is rather odd, but like you the stock DPF days were numbered so I didn't dwell on it.

Hope to have options on the DPF soon, just need to prove it will work....

Thanks, I might give this forced regen a try. I'll let you know how I go.

mate - if the reading is too high, this is not necessarily the same logic that applies if the sensor has failed. sounds like your car was trying to regenerate the dpf anyway.

you havent tried going for a long highway drive?

I drive my GT for 40minutes each way to work on a highway. I have never really noticed a DPF regen, maybe once or twice. But I'm pretty sure it gets hot enough for long enough during my normal usage to not need them much. The soot levels have always looked fine when I've checked using VCDS. So I wouldn't except my DPF is actually clogged.

The difference between the "implausible" and "signal to high" messages seems to be that the implausible message is when the signal is intermittently shorted to plus an the "signal to high" is when its always shorted to plus (have a look at the logs in the links I posted).

[jazd]

Bought a new sensor from the dealer this morning, $110

Old sensor 03G 906 051A


New sensor 076 906 051A


Good log from 5th August, note the DPF load at about 46% near the start. At 2881 you can see the RPM is constant and the EGR turns off and temp soars. The DPF load then decreases to 7%.


Bad log from today (faulty sensor still). You can see the DPF load is staying at 20% except for a couple of points where it seems to start working again. Group 070 value 2 seems to be the seconds that the car had been running the regen for. You can see it flattens out when the regen isn't active (DPF mode goes to 0). Not sure what Group 070 value 3 is exactly, its some sort of count. It seems to go up when the regen starts again, but not always. Its now at 4. Maybe the number of times its tried to regenerate or something?


The DPF light came on about half way through that second log. I should have pressed the mark button in VCDS but I was driving

[jazd]

2.0 TDI BRE Motor Differenzdruckgeber defekt: Dieselschrauber Community
This link seems to say that if you go into Coding II and type 11 it will adapt the ECU to the new sensor...


http://www.vweosclub.com/forums/showthread.php?t=4269
This details the voltages a guy was getting with a faulty sensor and good one. I wonder if it is possible to replace the sensor with a voltage divider giving the correct pressure reading for a healthy DPF and hollow out the DPF leaving the lambda and temp sensors intact...

[Greg Roles]

Cool will have to check that link out, can still adapt mine for the remaining DPF time!

Coring out a DPF is fine till it does a regen, and starts dumping fuel into your exhaust, then throws several errors. Very smokey affair too, so I am told. Car will eventually always do a regen, for if it doesn't meet the load parameters to regen, it defaults to kms, and sooner or later it will happen. I've played with mine at length, and no matter what you try, it always comes back on. Two levels of code too I am told.

$110 dollars cash money?? Geez you got had mate, sorry to say....mine was like half that!

[jazd]

Cool will have to check that link out, can still adapt mine for the remaining DPF time!

Just found out that is incorrect. I have found the correct code for the BMN engine. More details coming. The BMN engine actually has a VCDS label file in the German package. I am translating and comparing to the BKD English label file. Very helpful as it explains a hell of a lot more parameters. I found out that the count I was talking about above is actually the failed regeneration count!!

$110 dollars cash money?? Geez you got had mate, sorry to say....mine was like half that!

Yeah I thought so, I saw someone else that said $70. Price you pay for convenience I guess.