16706 - Engine Speed Sensor (G28) P0322 - 000 - No Signal - 2005 Touran 2.0TDI BKD

[skyegtb]

Hello, I'm looking for some advice re the above fault code. There is quite a story here, so thanks in advance if you read through it!

My car developed this fault code about 6 months ago resulting in random stalling, difficulty to start and glow plug light flashing. All the classic symptoms of the fault code.

I have a VAGCOM so checked all relevant info, cleared the code etc, but the fault was steady.

When cranking the engine the tacho is dead for the first 10 seconds or so, then it jumps in to life and after 10 seconds more cranking the engine will start. When the engine is running the revs are limited to 3500 approx and there is no turbo boost available.

So, I did the following: I removed the oil cooler to get access to the sensor and it's connection. I checked the wiring from the sensor to the ECU. The 3 wires gave good continuity between the ECU wiring and the sensor connector, but when I inspected the loom by removing the spiral wrap from the outside of the wiring I found that the spiral wrap had cut through the insulation in many places, not just to this sensor, but all over the loom. So, next, I sourced a 2nd hand wiring loom part number 03G 972 619 P. I checked the condition of it and found it to be good. I tested continuity between the G28 connector and the ECU plug and it too was good. Also, the resistance was measured on all 3 wires to this sensor at 1.5ohms - I assumed this was very good. I then fitted this loom, fired the car up and for about 20 minutes the car was running fine! No fault code and all was AOK..... Until, the engine suddenly stalled... The fault code and all the symptoms were back again. So, next I removed the G28 and replaced it with a brand new sensor. After doing that the car again worked fine for about 10 minutes, no errors, until the stalling happened again and the fault was solid. Next, I tried one more brand new sensor, but this time the fault remained with all symptoms........... At that point i waked away from the car as my head was done in, and that process had taken about a 2 weeks of the car being off the road waiting for the parts etc.

6 months on I decided to get this car going once and for all. The car had a long running (common) issue with a cracked cylinder head (visible clearly when the fuel injectors were removed) and massive smoking at start-up, and when driving hard, so I managed to source a replacement engine which was a great runner with no issues to swap the original one with. This should kill 2 birds with one stone, firstly remedy the terrible smoking issue of the original engine, and also hopefully remove any doubt about the crank seal G28 sensor mount - this, or the ECU, in my mind were the likely culprits of the G28 issue.

So, I got the engine swapped in 2 days without issue. The 'new' engine came with it's G28 sensor still fitted, so I left it where it was as this was a proven previously running engine and I didn't want to change anything there. Yesterday, got the engine started, it took a lot of cranking and a touch of easy start, but it fired up and initially ran OK, NO SMOKE either, yay! I started and stopped it a few times and scanned for codes, got a lot of random 'one time' codes that stayed away after clearing so all was looking OK, apart from the fact the engine would not rev past 3500 again! After a few more starts and stops I ended up with one single engine fault code: 16706 - Engine Speed Sensor (G28) P0322 - 000 - No Signal. Bo**ocks! So, that is where I am. I checked the wiring loom again, all is as before, good continuity on the wires from the sensor to the ECU, 1.5ohm resistance on these wires end to end.

What should I do next? Have I proved that the ECU is bad? I had a few other codes in the past (below) are they relevant? I am going to change the G28 next regardless as I still have one of the spare brand new ones.

Very much looking for advice, thanks in advance!!

17036 - Sensor Reference Voltage B
P0652 - 000 - Too Low

18062 - Please check DTC Memory of Instrument Cluster
P1654 - 000

[FLAPPERJACK76]

Wow that sounds like a headache. I maybe wrong here but I think sensor reference voltage b is definitely worth looking into. What I think this means is. ... you have an "a" circuit. .a "b" circuit and a "c" circuit wired into the engine ecu and on each circuit you will have various sensors and or actuators and if everything on this circuit is ok it will send back a reference voltage. ..for example let's say 5 volts, now to diagnose what's wrong you will need a reliable wiring diagram and then remove everything on circuit B one by one but putting each back whilst checking out circuit "b " circuit voltage reference till you get the correct voltage and then you will find what's causing the sensor reference problem.

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[FLAPPERJACK76]

Also have you checked measured values for cam and crank correlation reading's. What speed is crank and cam?

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[skyegtb]

HI and thanks for the replys. I will do some checking with VCDS tomorrow and report back - I seem to remember testing that 6 months ago and it shows the cam at 400rpm and the crank at 0 rpm, but the tacho was showing around 800 rpm. I have also been doing more searching on here and other forums reading of other people with very similar issues, but no definitive solution or conclusion. One chap suggested re-wiring the cable from the sensor to the ECU with new wire as he suggested that ANY degradation to the insulation on the wire there could lead to a defective signal. He changed the wires and got his car going. P0322 (16706) - Engine Speed Sensor (G28): No Signal - 2.0 TDI - VAG Diagnostic Software Discussion - uk-mkivs
Anyway, i will spend a couple of hours at it tomorrow and will report back.

[skyegtb]

Also, I found this: http://www.agthompsonfamily.com/vw/B...peedSensor.pdf

Not sure if it refers to a 2.0tdi, but the tests are similar to what I have done and also it refers to 1.5ohm resistance in the wires as being max accepted. My resistance it slightly over 1.5 ohms. I also like the last line in this which states 'replace ECM'...

[FLAPPERJACK76]

I would de pin the 3 wires from the ecu. Run 3 new wires straight to the crank sensor plug. I would just run them as a test and not worry about making them neat and tidy and if you get a result then put them in properly. You want as low resistance as possible. Make sure you use new genuine wiring with correct terminals and cross section diameters. Don't piggy back of any old wiring.

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[skyegtb]

Hi again, spent another couple of hours with the car. Checked the wiring again and with the engine running and G28 connected or disconnected I get the following results re cam and crank speed:

924 /min Engine Speed (G28)
0 /min Camshaft Speed


I checked the voltage etc at the G28 connector, again with the engine running. Pin1 = 1.0V, Pin 2 = 4.9V, Pin 3 = Earth. Checked the resistance on these wires again from connector to ECU wiring and got almost the same as yesterday, fluctuating 1.5ohm to 1.6ohm on all 3 wires.

Your suggestion of changing the wiring is sound and this needs to be done. I stripped down my old wiring loom to see if it is possible to connect new OEM connectors and wire to the plug, but to me it looks very difficult to do that. I read of a few people soldering new wires about an inch in to the wiring loom from the ECU connector. I think I would feel happier attempting that. I doubt the soldered join would make much resistance. So, to do this I need to find out the correct gauge of wiring and buy some wire. I have a spare 3 pin plug with connectors here ready to wire up. I do however have to say that if this works I would be amazed, as I find it hard to believe that these existing wires are actually that bad. In the ideal world I would fit a brand new loom, and hopefully then it would take away any doubt about the loom I am using. Also, ideally I would swap the ECU before doing anything else, as I cannot help thinking that the problem is there - bearing in mind my previous symptoms, it would be hard to imagine that the replacement loom I already fitted was defective in the same way as the original!!!

Anyway, ran the car for 30 minutes today, with the G28 disconnected the whole time. As usual, very hard to start with 20 seconds cranking to get it going, the tacho not moving for the first 5-10 seconds, then presumably the cam sensor taking over, the tacho moving and eventually the engine starting. During the running I did some logging and got some returning codes, but due to the MAF, the G28 and the fans being disconnected these mostly mean nothing, apart from the 2 I mentioned in the first post:

Address 01: Engine Labels: 03G-906-016-BKD.lbl
Part No SW: 03G 906 016 BQ HW: 028 101 190 6
Component: R4 2,0L EDC G200SG 6254
Revision: 12345678 Serial number: VWZ7Z0E1538751
Coding: 0000072
Shop #: WSC 01286 386 08256
VCID: 73EE026712B52FD9E4-8026


5 Faults Found:
16706 - Engine Speed Sensor (G28)
P0322 - 000 - No Signal
Freeze Frame:
RPM: 903 /min
Torque: 48.0 Nm
Speed: 0.0 km/h
Load: 0.0 %
Voltage: 14.29 V
Bin. Bits: 00001100
Idle Stabilization: 0.0°KW
RPM: 0 /min


17036 - Sensor Reference Voltage B
P0652 - 000 - Too Low
Freeze Frame:


18080 - Coolant Fan Control 1
P1672 - 000 - Open or Short to Ground
Freeze Frame:
RPM: 882 /min
Torque: 50.0 Nm
Speed: 0.0 km/h
Load: 0.0 %
Voltage: 14.29 V
Bin. Bits: 00001100
Temperature: 63.0°C
Duty Cycle: 9.6 %


16486 - Mass Air Flow Sensor (G70)
P0102 - 000 - Signal too Low
Freeze Frame:


18062 - Please check DTC Memory of Instrument Cluster
P1654 - 000 -
Freeze Frame:
RPM: 2478 /min
Torque: 136.0 Nm
Speed: 0.0 km/h
Load: 76.5 %
Voltage: 14.29 V
Temperature: 27.0°C
Temperature: 63.0°C
Temperature: 54.0°C


Readiness: 0 0 1 1 1

[FLAPPERJACK76]

Well after reading that ....Why is there no cam speed? Wiring sounds ok at g28 . G40 Should be half engine speed of g28. Have you tried a cam sensor. ? Is cam sensor live terminal 1 and earth 3 and what comes out of 2? If that's ok check at ecu from g40.

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[skyegtb]

Good question! Actually, when I looked back over some previous logging files I had the symptom of no cam speed was there previously as well. I also found some logs I did of when the old engine was last running OK and true enough it was 1/2 rpm on cam and full rpm on crank. This missing cam speed appeared at the same time as the G28 started playing up. Also, of note, all testing done today was with the G28 disconnected, so the only place the rpm signal could come from is the cam sensor. I presume this is the way the engine is able to run due to being built in the the ECU programming.
As I have nothing to lose i will check the cam sensor and it's wiring as well, and will report back when done. I am going to try to get an IMMO delete (plug and play) replacement ECU to try as well - there are a few people on eBay who offer these as I 100% want to rule the ECU out.

[FLAPPERJACK76]

Have seen a lot of wiring problems on these engine mainly around the gearbox area's and on any sharp points where the loom runs. I always remove the wire completely from the terminal plugs. You need a good depin tool and a lot of patience and really good eyesight. You can buy wires from Vag but they only come as repair wires 2 terminals one on each end and not very long.

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