Starting Issues - G28 Implausible Signal BKP - UK Volkswagen Forum

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planestone P Hi All, I appear to be a newbie to this forum, however, I'm sure I was a while back but can't find the details. I have a Passat Estate Sport with a 2.0TDi BKP engine. I've had it for about 7 years and been wonderful for most of it. Recently I have been suffering an intermittent starting fault. It first occurred last Autumn on a wet morning and presented as continuous cranking without firing. I down powered and tried again and it started, however, when selecting cruise control the display would show a '!'. I didn't get a chance to do a scan until a few days later and it didn't post a fault. Eventually it happened again and I got 16705 - Engine Speed Sensor [G28] P0321 - 006 - Implausible Signal.This is an intermittent fault which has occurred more regularly since. The fault appears to present on damp mornings when there's a heavy dew on the grass (and I suspect on some wiring). I know the first port of call in the online Bentley manual shows to measure the resistance of the G28 sensor, however, as time is precious I got the dealers to measure it for me and also replace it if No Fault Found. It was within limits and they replaced it as requested. The fault 'disappeared' for the next few months (or as much as an intermittent fault can disappear). The fault re-occurred following a night shift and there was a heavy dew, it has become more frequent since. From what I understand the G28 is a hall effect sensor with an excitation/measurement of 5VDC from the EEC which relies on that and the Cam sensor to calculate engine position and speed. If the G28 indicates anything out of tolerance the engine defaults onto just the Cam sensor and hence the cruise control isn't available. Some people in other forums for similar engines suggest that the signal can go out of tolerance due to a breakdown in the wiring which agrees with my experience. If this were to be correct and if my wiring did have a drop in insulation resistance caused by a nick or damage and then the dew conducts it to ground or the other wire to the sensor. Being an aircraft (electrical) engineer I'm keen to get testing and find the fault, however, I don't have much of the required documentation available. I'd be keen to measure the insulation resistance of the wiring with a meggar, however, I don't know whether the EEC>G28 wiring goes off anywhere else, I'd need to disconnect the G28 sensor and from what Crasher says here it's somewhat of a mare to get to. Apparently running in two replacement wires is a known good fix but I can't see where the wiring goes or any documentation as to correct routing. Does anyone have any experience of this fault and any suggestions please? As far as I can tell my options are: replace the wires, replace the wiring bundle, replace the EEC or live with the fault. My scan from today is below. I appear to have a low voltage issue also, I'm unsure if it's related. I've measured the battery after 12 hrs of not being used or charged and it shows 12.4VDC and 14.4VDC when the engine is on. It's a sealed battery with a green indicator. All of this makes me think it's not a battery/charging issue but potentially a ground issue but that could be a red herring. #1 · Sep 9, 2016 (Edited by Moderator) Hi All, I appear to be a newbie to this forum, however, I'm sure I was a while back but can't find the details. I have a Passat Estate Sport with a 2.0TDi BKP engine. I've had it for about 7 years and been wonderful for most of it. Recently I have been suffering an intermittent starting fault. It first occurred last Autumn on a wet morning and presented as continuous cranking without firing. I down powered and tried again and it started, however, when selecting cruise control the display would show a '!'. I didn't get a chance to do a scan until a few days later and it didn't post a fault. Eventually it happened again and I got 16705 - Engine Speed Sensor [G28] P0321 - 006 - Implausible Signal.This is an intermittent fault which has occurred more regularly since. The fault appears to present on damp mornings when there's a heavy dew on the grass (and I suspect on some wiring). I know the first port of call in the online Bentley manual shows to measure the resistance of the G28 sensor, however, as time is precious I got the dealers to measure it for me and also replace it if No Fault Found. It was within limits and they replaced it as requested. The fault 'disappeared' for the next few months (or as much as an intermittent fault can disappear). The fault re-occurred following a night shift and there was a heavy dew, it has become more frequent since. From what I understand the G28 is a hall effect sensor with an excitation/measurement of 5VDC from the EEC which relies on that and the Cam sensor to calculate engine position and speed. If the G28 indicates anything out of tolerance the engine defaults onto just the Cam sensor and hence the cruise control isn't available. Some people in other forums for similar engines suggest that the signal can go out of tolerance due to a breakdown in the wiring which agrees with my experience. If this were to be correct and if my wiring did have a drop in insulation resistance caused by a nick or damage and then the dew conducts it to ground or the other wire to the sensor. Being an aircraft (electrical) engineer I'm keen to get testing and find the fault, however, I don't have much of the required documentation available. I'd be keen to measure the insulation resistance of the wiring with a meggar, however, I don't know whether the EEC>G28 wiring goes off anywhere else, I'd need to disconnect the G28 sensor and from what Crasher says here it's somewhat of a mare to get to. Apparently running in two replacement wires is a known good fix but I can't see where the wiring goes or any documentation as to correct routing. Does anyone have any experience of this fault and any suggestions please? As far as I can tell my options are: replace the wires, replace the wiring bundle, replace the EEC or live with the fault. My scan from today is below. I appear to have a low voltage issue also, I'm unsure if it's related. I've measured the battery after 12 hrs of not being used or charged and it shows 12.4VDC and 14.4VDC when the engine is on. It's a sealed battery with a green indicator. All of this makes me think it's not a battery/charging issue but potentially a ground issue but that could be a red herring. See less See more Sort by Oldest first Oldest first Newest first Most reactions #2 · Sep 9, 2016 VAG Error Code: 16705/4514/000801 EOBD II Error Code: P0321 Fault Location: Engine Speed Sensor [G28] - Implausible Signal Possible Cause: Malfunction Indicator Lamp (MIL)(K83) active. Engine shuts off. Engine doesn't start. Tachometer inoperative. Glow Plug Indicator Lamp (K29) flashes. Wiring/Connector(s). Engine Speed Sensor [G28] loose. Engine Speed Sensor [G28] faulty. Possible Solutions: Check/Replace all faulty Wiring/Connector(s). Check Engine Speed Sensor [G28]. Read Measuring Value Blocks (MVB). Special Notes: The Engine Speed Sensor [G28] is also used as a reference sensor for the crankshaft position and correlates with the Camshaft Position (Hall) Sensor Bank 1 (G40) and Camshaft Position (Hall) Sensor 2 Bank 2 (G163). When found in a VW Golf/Jetta (1J/9M) or Audi A3 (8L) with 1.9l TDI-PD (AXR), check Technical Product Information (TPI) 2007067 which explains issues with electro magnetic interference. A modification to the wiring will fix this problem, extensive details can be found in the named Technical Product Information (TPI). Even though this Technical Product Information (TPI) was originally released for VW Golf/Jetta (1J/9M), a customer of ours came across the same issue on an Audi A3 (8L). When found in a 2004 VW Golf, Jetta, or New Beetle with 1.9l TDI-PD (BEW), check for Technical Service Bulletin (TSB) 2010461 (01-07-45 formerly 97-05-03) or 201463 (01-07-44 formerly 97-05-04) calling for a flash update to the Electronic Control Unit (ECU) and a secondary ground installation. VW Vehicles with the Most TSBs When is the code detected?: The P0321 code is triggered when the Engine Control Module (ECM) detects the signal is out of range. Description: Ignition failure sensor is used to check whether the spark ignition is occurred correctly or not and also used to tachometer drive. The sensor monitors the voltage difference between a resistance which is on the battery circuit for ignition coil. When the ignition coil works properly, the electric current through the resistance is detected as voltage drop. This is confirmed for every ignition event with the crankshaft sensor and the camshaft sensor. If Engine Control Module (ECM) detects a malfunction, no ignition is possible, so the engine would not start. If there is no ignition signal for a predetermined cycle for one or two ignition coils, an ignition coil circuit failure exists. As taken from my new EOBD II Fault Codes Software #3 · Sep 10, 2016 We have had a lot of problems with the G28 sensor on the EA188 engine and it is difficult to change as the oil filter housing has to be removed. If great care is not taken and a really good condition sharp 5-mm or later 4-mm ball ended hex key isn't used, the bolt head can strip out meaning gearbox , clutch and flywheel removal just to extract the bolt, even when taking great care, if the bolt fitted previously was compromised or over-tightened, it can be impossible to get the bolt out in the conventional manner, it is a very badly designed installation that we dread getting involved with. When fitting a new sensor we always fit a new bolt and very carefully torque it to the correct 5Nm, it is very easy to install the sensor at a very light angle so that the flywheel gently rubs on the senor and eventually it starts to play up again, we have also found that even when installed correctly, a failing DMF on a DSG model can also rub on the sensor and make it misbehave. We have also seen instances where the magnetic ring on the crankshaft oil seal holder start to come away from the oil seal and this wear the sensor. It can get the the situation of having to remove the gearbox to change the flywheel and also having to remove the sump to change the seal holder and senor for the later parts which costs £170 in parts (this also requires an expensive jig tool) and on earlier models like yours, you can also discover wear in the chain balancer shaft and oil pump drive system which means stripping the front of the engine down to chnage over to the gear drive system and that area alone involves £1500 of genuine parts plus the use of specialist tools. A failed G28 can easily write off an earl 3C Passat, I have sen it happen on a number of occasions. Gig to fit new seal holder Accessing the G28 with oil filter holder off G28 location in new holder Broken chain drive with tensioner shown below removed Broken tensioner Spur gear drive update system Insert Quotes Post Reply

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