having a tough time with my 2019.5 I6 petrol MHEV engine. cold starts are throwing P0521(85) . I'm assuming oil pressure too high? I'm also getting a P349D which is the 6th cylinder deactivation solenoid code. they are both intermittent. They will come on and off but mostly cold start in the morning . After 2 or 3 days the MEL comes on . New battery oil changed a week ago . added in 8 oz of seafoam but still having issues. biggest problem is Ready monitors obviously wont kick due to all of this .
Could i need a oil pump ? Any Range tech that can help?

 

Have you checked the ground on the car? Hard to tell if you need an oil pump. I would guess you have voltage issues not being stable at all times. I would also check the oil pressure sensor. Good luck and let us know what you find out.