I live in a cold climate. At least 8 months/year the temperature is around -5C / -15C.

I've started to believe that the PHEV isn't for countries with cold climates ( although the sister brands perform better!)

I've had several problems in the harsh winter with 1.4 TSI engine sensors, even went into limp mode couple of times, rattle sounds in cold starts, GPF not regenerating etc.

Eventually, I spent the whole winter mainly driving in e-mode. Even though it's not so cold anymore, (+7 C) whenever I switch to Hybrid mode, it's switching to ICE engine and keeping it running until the radiator temperature rises around 70 C. It doesn't even allow switching back to e-mode. It's momentarily displaying a message "You need to keep the engine running for longer".

I'm wondering if this is a bug or a built-in function.

It’s chemistry. Batteries don’t work very well, in the cold as the chemical reaction markedly slows down. All battery performance is significantly degraded but it does no permanent damage. Most modern cars can heat batteries to keep them in an optimal range. I don’t know the situation with IV specifically. For completeness high temperatures also impairs battery performance but in addition does permanent damage.

19 hours ago, whippersnapper said:

It’s chemistry. Batteries don’t work very well, in the cold as the chemical reaction markedly slows down. All battery performance is significantly degraded but it does no permanent damage. Most modern cars can heat batteries to keep them in an optimal range. I don’t know the situation with IV specifically. For completeness high temperatures also impairs battery performance but in addition does permanent damage.

Yes, but, that's not what I'm stating. When I keep the car in e-mode, it runs on battery, perhaps at lower capacity during the cold days, but when I switch it to hybrid, it turns on the ICE, whilst displaying the message on the left side of the driver dashboard momentarily. Then, the ICE stays on until the engine gets up to 70 C then switch back to hybrid mode. I'm just trying to figure out if this is a normal automatic response or is it another bug.

Skoda dealt with the issues of Octavia PHEV,s and cold weather or engines not being run much. They discontinued manufacturing them. But still there is the Superb and Kodiaq. Time will tell how these go.

1 hour ago, Octawia said:

Yes, but, that's not what I'm stating. When I keep the car in e-mode, it runs on battery, perhaps at lower capacity during the cold days, but when I switch it to hybrid, it turns on the ICE, whilst displaying the message on the left side of the driver dashboard momentarily. Then, the ICE stays on until the engine gets up to 70 C then switch back to hybrid mode. I'm just trying to figure out if this is a normal automatic response or is it another bug.

I do a lot of short distance driving in electric mode on my 2021 PHEV. About once a month it insists on sunning on the ICE for about 10 miles, after that it will allow a swich back to electric mode.

There is a huge difference in climate /ambient temps with the UK and Bristol area and Finland.

2 hours ago, Octawia said:

but when I switch it to hybrid, it turns on the ICE, whilst displaying the message on the left side of the driver dashboard momentarily. Then, the ICE stays on until the engine gets up to 70 C then switch back to hybrid mode. I'm just trying to figure out if this is a normal automatic response or is it another bug.

Hard to say without seeing. That engine will run till it is hot is absolutely normal. But during normal operation there shouldn't be any messages on the left. It only is supposed to show message on infotainment if you attempt manually to bring it back to E-mode before the engine is warm. All I can say is I had an issue with engine starting for no reason and message on the left saying it needs to run longer, but that was some 12V system gremlin after my 12V battery was replaced. Hardly related to what you have.

4 hours ago, Octawia said:

Yes, but, that's not what I'm stating. When I keep the car in e-mode, it runs on battery, perhaps at lower capacity during the cold days, but when I switch it to hybrid, it turns on the ICE, whilst displaying the message on the left side of the driver dashboard momentarily. Then, the ICE stays on until the engine gets up to 70 C then switch back to hybrid mode. I'm just trying to figure out if this is a normal automatic response or is it another bug.

Fair enough, I have no idea about this models details specifically (salesman tried to steer me towards very discontinued models but they weren’t successful). From first principles it makes sense that the ICE would run when very cold to warm the Li-ion battery to operating temperature. If the ICE engine starts it makes sense it should run to at least fully warm up otherwise you are getting water condensate in the oil and never removing it.