Focus oil consumption

[caretech]

Have a 1.4 54 petrol focus in with enging fault diag report " Catalyst system efficiency below threshold bank 1" pos due to oxy sensor at cat ? but enging also using lots of oil. No leaks so must be burning ? prob what causing fault in 1st place. Any one know of known fault on this model of enging. Could oil be pulled through breather system as no exsessive smoke on acceleration and doubt piston ring trouble. Thank for reading.
Grahame

 

[wotan]

The engine breathing system would be a good thing to check, has the car been overfilled?
Sounds like cat is partially choked too, take it for a good high speed run, legally of course, this might help.

Wotan

 

[Mursal]

They do like to burn oil

 

[wotan]

They do like to burn oil

But caretech stated no excessive smoke?

Wotan

 

[bhm1712]

Check the Positive crankcase ventilation valve to make sure its opening when the engine is on (its basically a none return check valve which allows the pressure inside the crank case to exit and go back into the intake) If this is stuck closed the pressure can cause oil to blow by the oil control rings and burn off during combustion.