Hello all
2011 Chevrolet Traverse LS 3.6L V6 198000KM automatic transmission I just had my spark plugs replaced per my maintenance schedule. One of the spark plugs looks rusty (see picture). I have an intermittent p0420 code. My LTFT before spark plugs replacement on bank 2 was around 10%-15%, now it's around 4%.
What does the rusty spark plug indicate? Could it be causing p0420?
Thanks
Has it ruined the Cat? How do I know?
Since the rust is just on the outside of the plug and the combustion chamber end looks OK (at least as far as I can tell from the angle of the photo) it is probably unrelated. The cat could be wearing out or it could be an O2 sensor problem.
This video demonstrates how to test O2 sensors. (It's on a Jeep but would be applicable to other vehicles.)
https://www.youtube.com/watch?v=iVjJwJCt2Hg
That rust is on the outside of the spark plug so it looks like some moisture got into the recess where the plug is located. It could have just splashed up, or it could have sprayed in there from a pinhole leak in a hose if one runs by that location. (I guess the worst case would be an external head gasket leak that's dripping there.)
What must I do now? Thank you.
You need to observe that location while the engine is running to see if any coolant is leaking in there.
Has it ruined the Cat? How do I know?
Should I put cleaner in the fuel tank and hope for the best?
Was the spark plug rusty just on the outside or near the electrode on the business end? It's hard to tell from the photo. How old were these plugs? If the rusted plug wasn't grounding properly, it would show a misfire for that cylinder in a scan.
I think it's just on the outside, not on the the threads side/electrode side. See picture. https://ibb.co/pwMW055