Hello - My parents have a 2007 Nissan Altima which made a loud ticking noise suddenly before their car turned off. The car will go into auxiliary mode, dash lights up, but the motor will not even try to turn over. I tried using a scanner, but it would not read codes which lead them to believe it was possibly an ecu problem. Well, it was towed to the dealership and they discovered oil got all into the spark plugs. Naturally they recommend new plugs and a new valve cover gasket. However, what could have caused oil getting into the spark plugs? And, does this mean there is a larger issue? Car has a 175K miles.
Oil gets into the spark plug tubes (and onto the spark plugs) ((and ignition coils)) when the spark plug tube seals in the plastic valve cover(s) fail.
You didn't say if they have the 4 cylinder engine (1 valve cover) or the 6 cylinder engine (2 valve covers) but it doesn't matter.
You can't replace the spark plug tube seals in the plastic valve cover(s) on either of those engines. You have to replace the valve covers. Of course you have to replace the valve cover gasket(s) when you do the job too as well as the spark plugs.
I just did a valve cover, valve cover gasket replacement on a 4 cylinder Altima a few months ago. Same problem that you're having now.
One of two things happen when the spark plug tube gasket fails.
1) The oil shorts out the ignition coil, destroys the ignition coil, and the cylinder(s) doesn't get spark.
2) The spark shorts on the outside of the oily ignition coil to the outside of the oily spark plug instead of jumping the spark plug gap and the cylinder(s) misfires but the ignition coil isn't damaged.
So it's important to disassemble any coil that's covered in oil that still works and clean all the oil out of the inside and off of the outside of the ignition coil. I used dish soap and water.
The image shows the 2 coils on the right are covered in oil from leaky spark plug tube seals
https://www.youtube.com/watch?v=0_OhoslnS_M
@jack62 Thank you!!