2-cylinder mode no longer working

[arciere]

All of a sudden, after being parked for a week or so, on my Golf 1.5 TSI manual the "eco (2-cylinder) mode" has stopped working completely. On top of that, the gear change indication has increased the RPMs considerably. For example, it now asks me to downshift to first gear unless I am doing at least 13mph, while previously it was perfectly happy being in 2nd gear at 8mph. Similarly, I used to get prompt to go to 5th gear as slow as 30mph on a flat road, while now that happens at 36-37mph.

I know that I'm still the one changing gears so it's not a big issue, but combined with the fact that 'eco-mode' no longer works, I suspect something's wrong somewhere. Apart from this, the car feels completely as before.

Any thoughts?

 

[tos]

I think that the engine tries warm up for burn/regenerate GPF (particle filter).
You should drive highway with high RPM

Regeneration
With normal vehicle usage, the filter cleans itself. If the filter is unable to clean itself (e.g. if you only make short trips for an extended period of time), the filter can become blocked with soot. The particulate filter needs to be cleaned (regenerated).
Noises, light odors, and increased engine speeds may occur during the regeneration. The radiator fan may continue to run while driving and after turning off the engine.
To assist in particulate filter regeneration, Volkswagen recommends avoiding driving short distances too frequently.

The soot in the particulate filter is burned periodically at high temperatures. The yellow

indicator light does not turn on during a periodic regeneration.

 

[arciere]

Thanks, that would make sense, although can that happen at 5k miles only? I do a mix of short and long trips, but it's weird that it happened after a 20-mile trip yesterday.

 

[tos]

Maybe the particle filter started to get full, and then it wants to start regeneration process...

https://userguide.volkswagen.de/w/en_GB/welcome
Search particle filter

 

[SRGTD]

@tos - you beat me to it! I’d hazard a guess that @arciere ’s car is performing a forced / active GPF regeneration. I’ve experienced (I think) 3 of these in my 2020 2.0 litre Polo GTI+ in 3.5 years / 15.4K miles. The tell tale symptoms when my car performs an active regen are;

• Slight lumpiness to the engine idle and slight hesitation when accelerating
• louder exhaust note
• a hot smell
• stop start does not work
• engine cooling fan running
• significantly worse fuel consumption while the regen is happening (my fuel consumption increases by around 30-35% during a forced / active GPF regeneration)

The regen takes around 25-30 minutes in my car and when it’s finished, everything is back to normal. If I’m aware (I am because of the above symptoms) it’s in progress when I’m nearing the end of my journey, I’ll try to extend the journey to give the regen an opportunity to finish. If not, it’ll recommence the process on the next (and subsequent) ignition cycle(s) until the regen is completed.

A high proportion of short journeys on a cold engine will mean more GPF regens than someone who’s driving mainly long journeys with the engine at optimum operating temperature.

 

[arciere]

I drove about 10 miles today on the motorway at around 3,000 RPM in fifth gear, still no change.

I have a OBD reader and on the app I could see that "PF regenerate status" is currently set to 'YES'. Could that be a confirmation of what's happening? Do you know how much longer the car will be in this state (never happened to my previous Golf, same engine and around 30,000 miles).

 

[tos]

I think that you should drive more...
Did you check what oil temp said when you was driving?