Hello, I have a 99' S80 T6, the car had a check engine light that came on and I pulled the code and it was P0236, P0300, P1181. First thing I did was change the spark plugs to narrow the trouble shoot down. When I removed the spark plugs (starting on passenger side) the left 3 cylinders had a black coated surface. Then I removed the next 3 and they had a white powdery coat( I think that means its working fine since its burning). My concern was the first 3 plugs that were removed. Seems like they are either not firing or oil leaking into the cylinders. anyone with an input on this?

 

what do the codes mean ?

the plugs with the oil on them are fouled, i think that means the piston rinds on those cylinders are shot, the white coating on the other three is carbon build up, its fine more or less thats a byproduct of combustion and happens with age

if your piston rings are shot thats really bad, see a mechanic to make sure

 

I thought I read somewhere that when this occurs, its because the O2 sensors are sending a too rich signal causing bank one to run rich. I didn't look up your codes, but i don't think all three rings went bad at the same time. I think its time for some new O2 sensors.

 

hmmm Looks like Ill be back at the shop on monday then. Probably do a compression test and check o2 sensors. thanks