VAG-COM: Blinking Check Engine Light Diagnosis

Dear forum members,

I have a Golf III TDI with an AFN engine (manufactured in 1996) that is happily driving around in southern Spain.

The timing belt needs to be replaced soon. As I've done with my other vehicles in the past, I'll be doing the replacement myself.
I have a VAG-COM device. This weekend, I tried using the TDI timing checker, as the injection timing needs to be checked after replacing the timing belt.
I noticed the following: When I'm at measurement block 000 and click on TDI timing, I observe that the engine speed changes and the engine runs more roughly. Additionally, the glow plug warning light starts flashing.

I've done a little searching in the forum, but I haven't found anything related to this. Is it normal for the indicator to come on? Probably because the control unit detects that someone has "logged in" and recognizes this as an error?
Or am I fundamentally doing something wrong?

Another thing is that I can't seem to get the coolant temperature above 80º. I guess I'll have to drive the car for a while first, and then test it, right?
According to VAG-COM, the temperature does not increase when the engine is idling. Consequently, the value for the injection timing remains below the green line.

As you can see, I'm new to this field, so I really appreciate any information you can provide.

Greetings from Andalusia.

Kiko.

Quote:

Here's what I've noticed: When I'm at measurement block 000 and then click on TDI timing, I notice that the engine speed changes, and the engine runs a bit rougher. Additionally, the glow plug light is flashing.

That's normal...

Dear Malte1408,

You're welcome.
"Well, that's a relief. I've learned something new..."

Regards,

Kiko.