Turbo Unit underboost and oil level too high Yaris

[CheerfulD]

We have a Toyota Yaris TR 1.4 SDR diesel, 2010 plate with 63,000 miles on the clock.  The engine warning light came on and I took it to our local garage to be diagnosed yesterday.

Two fault codes came up - P252F which is that the oil level is too high and P0299 which is tort turbo charger unit underboost.  The garage are saying that they can either look to clean the turbo charger but they have limited success at a cost of £200 (but could very possibly result in needing to replace the turbocharger), or they can replace the turbo charger which will cost about £1000.

Typically, we were about to look to sell the car, and consequently are unsure as to what to do to fix the issue for sale and loose the least amount of money. 

Has anyone had any success with cleaning the turbo charger?  Is there anything to look for that might make the clean more likely to succeed? Is the oil level too high code related to the turbo charger issue?  We haven't added any oil to the car ourselves and its serviced regularly at the garage.

Greatful for any input if you have had a similar issue and what resolved it.

Many Thanks!

[Madasafish]

63,000 miles for a 10 year old diesel suggest lots of short journeys - which are bad for diesels.

It leads to carbon build up in the EGR valve , inlet manifold and turbo And DPF (if fitted) ..  I assume there is a DPF on this engine but if there is and it needs to regenerate- clean the system - it injects more diesel into the engine to burn off the excess fuel and clean the DPF. Too many short journeys and it does not work and the excess diesel flows into the sump giving an increased oil level reading.

So if you use the car for short journeys and it never gets warm, not only will it carbon up,,, but excess diesel  can flow into the oil..

In that event cleaning the turbo on its own will not work for long. You need a clean of : EGR valve...DPF . intake manifold and turbo outlet  , a complete oil and filter change   (assuming no DPF). And the DPF cleaned.. or replaced...  You might get away with just  DPF cleaning (which is what I assume the garage meant)

I have done this on our 2004 Jazz D4d.. - excluding the turbo  oil pipe clean.. It takes hours and is very messy..

Get it fixed as a bodge and sell asap. That is a DPF clean. If you are driving under 12,000 miles a year and mainly short journeys.. you should not have a diesel...unsuited for the short runs and never getting hot.

I would also when fixed drive it at least 30 miles at over 3500 rpm in every gear to try to clean it up a little. And preferably nearer 5,000rpm  (which is what we do to pass MOT smoke tests - every year)

I am surprised it passes a MOT smoke test.

see also https://www.honestjohn.co.uk/forum/post/index.htm?t=101892

[flash22]

The oil is probably highly diluted - it's probably not had a proper oil change in some time, find another garage or DIY

first step is to do an oil and filter change and give it a good long run, imo yes the codes could be related

[mrfixer]

Oil and filter change.

With half-full tank add a bottle of Wynn's Diesel extreme smoke eliminator.

Head to the motorway and drive for about half an hour. Drive in third gear at high RPM - near red line - for 2-3 minutes. Then change into top gear for same amount of time. Then back into third again etc...repeating for the duration of the journey.