2008 Jetta 000802 - Engine Speed Sensor (G28) Fault

[Crasher]

If you clone it there should be no issue, I had to last week with an A4 TDI as my ODIS laptop's wifi failed so I just cloned a used ECU instead of using ODIS.

[Skezza]

Understood. Thanks mate.

If i plugged in the ECU without clone, is there any risk of bricking the cluster? Just weighing up my options as while I've done many a hot air SMD removal, there's always a first time it could go wrong hence preferring an IMMO OFF first (but they're not 100% first time usually).

[Crasher]

I prefer ODIS reprogramming, I have had a couple of cars brick themselves after an ECU change but not irrecoverably.

[Skezza]

I prefer ODIS reprogramming, I have had a couple of cars brick themselves after an ECU change but not irrecoverably.

I've ordered the ECU. Going to clone the EEPROM in the first instance and just fire it up. See if the issue persists. I suspect it'll run like dogs dinner at first but with it being for the same engine, I hope, touchwood, that it sorts itself.

I suppose what I could do is run it up to temp and subsequent failure conditions and then see if swapping the ECU then causes it to fix itself?

[Crasher]

Old ECU’s are becoming a serious PITA as I cannot find anyone I trust to properly check or repair them. I had one done by ACTronics a couple of weeks ago and they said there is nothing wrong with it but I am convinced they are wrong as whatever they did to it highlighted two definitely faults that were not visible before on THREE previous ECU’s one of which is definitely faulty. There is Bosch in Germany who will “recondition” it for €500 but what if I get the same result as they have let me down in the past.

[Skezza]

Old ECU’s are becoming a serious PITA as I cannot find anyone I trust to properly check or repair them. I had one done by ACTronics a couple of weeks ago and they said there is nothing wrong with it but I am convinced they are wrong as whatever they did to it highlighted two definitely faults that were not visible before on THREE previous ECU’s one of which is definitely faulty. There is Bosch in Germany who will “recondition” it for €500 but what if I get the same result as they have let me down in the past.

Well for this car, it'll probably be a death sentence if I can't repair it. I can't justify £110 per hour to a specialist. Electrical gremlins can be so difficult to track down. This is my lazy attempt. Fingers crossed I suppose.

[Skezza]

I'm back.

So, new ECU has arrived. I've IMMO OFF'd it, in the first instance, but might just clone the eeprom off the one in the car. Was a pain to get apart. It had some thermal compound I've not seen before that had welded... However I can't help but come back round to the idea that this might actually be the crank sensor. I wouldn't say I've done a whole lot of sleuthing here, but I decided to plug a little cheapie bluetooth OBD dongle and run torque while the issue occurred to see what was logged.

I must have cleared the code and let it trigger again about 10 times and the same fault was logged every time:
P0726 Engine Speed Input Circuit Range Performance

Searching for that code brings quite a few people who have experienced it, same engine, same symptoms (quite a few worse) and a good number of them saying a new crankshaft sensor did the trick. OEM only... don't go aftermarket.

I've also started to experience more of the symptoms you would experience with a failing crankshaft sensor, such as weird spluttering and bouncing forwards, stalling unexpectedly etc. It's also getting worse. Some days now the car won't start for a few mins after stalling.

I spoke to the original garage again and asked them for a flat quote on how much to replace the crank sensor? No further diagnosis.
They said something to the effect of
"£150 if we don't have to split the gearbox, £400 if we do and it all hangs on whether we can remove a single bolt. If we can't, it's a gearbox out job"

So I know very little about this bolt, but as I understand, it's behind the oil filter housing. What's the chances of it actually coming? Is it necessary to remove the gearbox?

Is this something I could do on my drive, realistically? I'm a moderate mechanic... can roughly find my way around, but definitely not garage material.

[Skezza]

Any thoughts @Crasher ?

I've noticed that there's no specific temperature that it fails. Sometimes it happens at 55 degrees, other times as high as 72 degrees.

Tbh, the running temp seems a tad low (only gets up to like 78 deg) but I don't think it's related.

[Skezza]

Back again.

Had a go at fitting new immo-off'd ECU today. Car absolutely would not start but logged yet again the same crank sensor error + a new one I've not seen: 005732 - PD Unit Injector; Cylinder 2. Guessing that's unrelated to the main issue though.

It logged nothing related to the immobilizer. No idea if it's a faulty ECU or just because I've not paired it in any way at all. Reinstalling the original ECU works, but obviously I'm letting it cool down before trying again.

Doing some reading up on that and will probably clone the EEPROM, especially if IMMO-OFF'ing hasn't worked