AVF TDI im Passat 3BG: Kaltstartproblem | Posts 32+

Hello!
Yes, that's exactly what it sounds like. It's a burning sound, a regular one. Estimated to be happening every 2 revolutions. That could be right .

My last desperate attempt was: removing and opening the black relay in the engine control unit box (which is the only one in there). No obvious faults were visible. I then put it back in. And I disconnected the two connectors from the engine control unit (as far as I could tell, there were no obvious contact problems there either). I did this several times in a row. Since then, there have been no more problems . But it could also be a coincidence, I have no idea. But it's been at least 3 weeks since it last misbehaved.

I haven't found the relay for the engine control unit yet. The black one in the box near the ECU should be for the glow plug system, right? But where is the relay for the transmission control unit (TCU) then?

Greetings.

Hello Mike,


Today, my car wouldn't start at all! After about 10 seconds of trying to start it, it finally started, and there was an error message in the error log: "OT sensor implausible signal" . But that sensor is new!!!
I'm going to check the ring on the crankshaft (OT sensor) today.
I have to work, then I'll write again.

Best regards,

Exactly the same as with me. The G28 (crankshaft sensor, which is also new in my case) is showing an implausible signal.
We have exactly the same problem. But don't be fooled by the G28. My said that it only gets into the memory because it starts up in that way, and the sensor is giving an implausible signal. This doesn't mean that the sensor is broken, which also makes sense. Something else must be causing the malfunction, and the G28 is just a consequence of that. But what? In my case, it's currently running 'still' normally. So far, there have been no more startup problems. But I don't trust any of it.

Let me know when you've made any progress. You can see my list of parts that I've swapped out above. NONE of them have made any improvement!

Greetings.

Hello

"You might be right about the sequence of events. If I check the engine speed during startup with VAGCOM, it seems correct, and the tachometer goes up to about 300 RPM, then briefly drops to zero, then goes back to 300 RPM, and then the engine starts. I suspect that the moment the tachometer drops to zero is when the error code is logged (because the check engine light comes on at that time). In my opinion, the engine control unit is temporarily treating the camshaft sensor as a substitute. However, this only seems to happen if the engine doesn't start for a long time. I experience these minor starting difficulties almost every day, but only in the morning. Then the car sits for the whole day, and in the evening, it usually starts without any problems."
I still believe it's a fuel problem, but I can't find any bubbles in the fuel lines... hmmm, maybe the fuel pressure from the tandem pump is too low. Is it possible to measure that? It's directly attached to the engine head. I'm also going to disconnect the coolant temperature sensor in the morning, before the first start, to get a richer starting mixture and see how it starts then.

Hello!
Yesterday, he did it again, for about 2 seconds, and the outside temperature in the garage was 21°C.
I am still looking for:
a) to the relay of the engine control unit.
b) after the check valve in the diesel line.

"I have these two new parts lying around, but I can't install them because I can't find the right place for them. I haven't replaced the G62 coolant temperature sensor yet, but I'll be getting a new one soon to rule out all possible sensors. The only annoying thing is the mess with the coolant. How do you guys deal with that?"

Does anyone have a suggestion as to where these things might be mounted?

Florian, have you made any progress?

Best regards,

Hello!

Yesterday, I replaced the G62 module again. The error is still present. It really seems like there's not much else left to try.
"What I noticed when replacing the G62 is that the tandem pump has a kind of "fluff" or "fur" on the side of the housing. This means it's sweating slightly, and dirt and dust are forming this fluffy coating. Is this an indication of a leak in the fuel system or a defect in the entire tandem pump, or do all tandem pumps sweat slightly, and is that normal?"

Greetings.

......and the problems continue. Today, suddenly while driving, the message "CHECK BRAKE PADS" appeared. I thought, "Okay, maybe it's finally time after 95,000 km." However, a visual inspection and restarting the engine showed something different. Visual inspection: approximately 3-4mm of pad material remaining, and after restarting, the warning message disappeared. What I don't know is, does the warning message appear delayed after turning the ignition on, or should it remain on and appear immediately every time the ignition is turned on, until it is reset or the pads are actually replaced? Does anyone know? I only drove into the garage, parked, and briefly restarted the engine. At that point, there was no warning message. Is that normal?

Thank you for your help.

Take a look at the linings on the inside.

The linings tend to wear out faster there. Presumably, the cable for the wear indicator is "almost" completely broken and has intermittent connectivity.

And if the contacts are really still in good condition, try disconnecting them and spraying them with contact cleaner. That happened with my Passat once.

Thank you for the help. I drove again a little while ago. After about 1 km, I heard "peeeeep" and the message "CHECK BRAKE PADS". At a traffic light, I turned off the ignition and then turned it back on. Since then, I haven't received any more messages. Strange, right? I thought the instrument cluster was so intelligent and would "remember" this message, like with a "SERVICE NOW" message, for example .

Okay, so it's theoretically possible that there's now a transition phase where you might see the warning light appear, then it goes away again, and then it reappears, etc. This could go back and forth for a while until it eventually always comes on "immediately"? Can anyone confirm this? I always thought that the warning light would appear once and stay on until you actually replace the pads .

Greetings.

... In my case, the warning light came on and stayed on until the pads were replaced.

Sven.

Quote:

I always thought that the warning light would come on and stay on until the pads were actually replaced.

I'm not entirely sure how the company "handles" things either.

but how is the system supposed to distinguish between new brake pads and simply a regular pass-through?

or another option:

Does it really say to check the brakepads? It's possible that there's just not enough brake fluid (which would indirectly indicate a worn brake system [or something worse]).

I'm not exactly sure how things are "connected" or "related" to each other at VW.

Hello everyone!
"Of course, it's clear that the ABS (Anti-lock Braking System) doesn't 'see' that the pads are new. Therefore, it's logical that when there's contact again, it appears to the ABS as if new pads are present. Okay, but could it really be that the pads make contact and then lose contact again? Or does this definitely indicate a cable problem?"

It's definitely the "CHECK BRAKE PADS" message, and the yellow brake symbol keeps illuminating. The fluid level is okay, and otherwise, the car is running fine. It's possible that the inner brake pads are worn down. But why doesn't the warning light come on all the time? I thought a brake contact would only trigger once.

Greetings.

hello.
As mentioned, I'm not very familiar with VW advertisements.

If I remember correctly, I experienced this "sporadic display" issue once or twice during my training (so the phenomenon is quite rare).

However, the contact point will be worn down... If you use the brakes as gently as my old car did, I think it's quite possible that you can still drive a few more kilometers (until the light comes on permanently).

The following options remain:

- Check the inner lining (from below/or by removing the wheel), or do it right away.

- Remove the interior lining -> inspect the wear cables.

- bridge wear cables.

Hello!
Die Anzeige kommt jetzt immer öfter, ja eigentlich fast immer sofort bei Zündung=Ein. Das stimmt, ich bin ein Wenigbremser und seit dem Aufleuchten nur Stadt gefahren. Also wird das schon stimmen, so wie es ist. Ich werde heute Beläge holen und diese tauschen. FeReady.

Thank you again.

Greetings.

"Linings replaced. Everything is okay again. The cable on the inner lining was really close to falling off and was completely worn. Therefore, there is a transition phase where it might sometimes make contact and sometimes not. Finally, it was constantly beeping immediately after starting today. Now it's working properly again. But I now have another problem regarding the starting behavior. I thought I would replace the wiring harness of the PD injectors in the cylinder head as a precaution. But it's easier said than done. When installing the TDI engine lengthwise, you can't simply slide the wiring harness in and out because of the fuel rail. It's probably very easy to do with a transverse-mounted TDI. But how do you do it in a Passat or an A6? You can't bend the wiring harness too much, or it will break. And do you really have to remove the engine, or even the cylinder head, for that? Does anyone have any tips?"

Thank you.

Greetings.