Starting the vehicle this evening with a full battery, the SI4 engine started immediately (itself unusual) and then displayed an “OK to drive - reduced engine power” warning. I had to set off home, but things definitively weren’t right:

1) Wouldn’t shift into EV mode.
2) The engine was running very unevenly and juddering.
3) The engine stalled a number of times and struggled to make it away from the lights.
4) There was a discernible whining sound (turbo?)
5) The SI4 engine achieved 11 MPG on the 5 mile journey home.

I managed to make it back and called LR Assist. It was late and there were no mobile LR techs available, so they sent an AA patrol. Of course when they arrive, the vehicle starts and drives fine on the engine (and EV engages now too).
Frustratingly their diagnostic equipment was unable to read engine error codes on the PHEV, but did bring up a transmission error P0C1B (Driver if electric trans. oil pump - voltage out of range). Should LR be able to see more?

I need to drive from London to Cotswolds tomorrow for a friend’s wedding and don’t know if I can trust the car to make it.

Does anyone have an idea as to what the problem might be, or recommendations? I’m already fastidiously documenting everything as it occurs, preparing for a protracted battle with LR over an intermittent recurring fault!

My PHEV frequently starts with Si4 engine although the battery is fully charged. It can occur from start in the morning or after stopping at the post office on my way home from work.There is no consistency, one day EV all the way, the other Si4 from start or after a stop. No messages on the info display and no noticeable reduced power.

Mine also sometimes starts with the engine (frustratingly it seems to happen most often when I'm demonstrating the electric powertrain to a friend!)

However, I've never had the problem that the OP describes, specifically the "reduced power" warning. 2024 Range Rover P550e AB