CVT gear change

[Wiggo]

We have a 2012 Yaris T Spirit CVT bought new and now with less than 23k on the clock. A few days ago it suddenly changed down and then when the revs rose it changed back up. The car was fully warmed up on a flat dual carriageway at around 40mph. It happened a few times on similar local roads so contacted the local main agent. A tech took me out for a test drive with no recurrence so the car was left with them for 3 days whilst they did more test drives with no problem. Hooking up their laptop there were 5 historical fault codes logged, p0339, p1603, p1604,p1605 & p1550. Picked the car up today and on the journey home it did the same thing - changed down and then up. Only the once this time. Anyone out there had a similar problem? Up to now the car has been trouble free and really good to drive.

[TomdeGuerre]

I've run a CVT Auris for a couple of years now without any problems like what you're having. I never use mine in manual mode, do you? I've got to admit I'm concerned with that box of tricks which is why I went with a Toyota main dealer service package so there's no hitches should a warranty claim arise. I am prepared to bet that anything to do with that CVT box will be expensive.  

[Lustral]

Does this happen when you are going downhill by any chance , and you tap the brakes ? This will make the engine hunt and then use more RPM to slow you down. All normal ? 

However if this is doing it on a flat road then this needs to be looked at again. 

[Wiggo]

I've never used the manual change either. Being idle I stick the car in D and leave it. As for the paddle change it may be ok for Lewis H and his friends but for a Yaris driver of my advanced years - nooooooo!

The downhill engine braking was quite surprising the first time it happened as it seemed to change down too many gears. The revs rose more than I'd imagined but it sorts itself out once on the flat. (At least it did until last Saturday)

The car is back into the main dealer next week so I'll post again with the outcome.

[Wiggo]

Finally got the car back on Friday 11th. Drove home, sweet as a nut. Saturday morning got no more than 200 yards on a cold engine and it stuck in gear. Tried to use the manual operation and that wouldn't work either. Stopped for a few minutes, tried again and the car ran perfectly and has done ever since! I contacted the main agents again and got absolutely nowhere. The impression I get is if it's running ok, leave it. I asked if they wanted to check the fault codes for future reference - silence. Good job we're in the AA!!

[MEP's Yaris GS]

Sounds like a multimode auto gearbox rather than CVT.....