Does he have an oiled air filter (ie: K&N or AFE or other)? Seems as though folks can over oil them and can cause some oil fouling in the intake system especially on sensors. Or if its engine oil the turbo would be leaking internally and bypassing into the intake. That could lead to a run away engine where it runs on oil up to full throttle and cannot be shut down. I better let some real engine folks explain how that happens as I'm not a Holset expert.
But definately figure it out! Either situation is not good.