I purchased a set of Denso FXE22HP11 for my 2008 Sport Sedan in August 2015 from my local Nissan dealer. This week, exactly 1 year later, I had a P0301 trouble code. I removed the #1 cylinder plug and it looked bad (photo attached). The remaining plugs were in the same shape except for #2 cylinder which looked much better (photo attached). I then noticed the #2 plug was a FXE24HP11. I checked the plug boxes but didn't verify the plugs before installing them and it appears a 24 snuck in (lesson learned). I have about 12,000K on the plugs 65 % city driving and 35% highway.

Has anyone had Denso dealer plugs fail so quickly or is this expected? Should I use the 24's to get longer life? I know it's a colder plug than the factory 22's, but it seemed to hold up better. Could there be an underlying problem causing the plugs to fail so quickly? Is the Denso TT line a better option?

Thanks for your input.

 

Hmm, a couple thoughts:
1) If your engine is running properly, there is certainly no need for a colder plug. In fact, it would actually be detrimental to run colder plugs in a stock configuration. Likewise, there is no reason to run another line of plug, as the stock plugs are usually solid for 100K+ miles.

2) The part numbers you show are slightly off (besides the heat range). The correct part number for the car is FXE22HR-11 (Denso #3442)

3) The fact that you are killing plugs, getting misfires, etc. is clear indication that there is something wrong with your motor. The spark plug didn't cause the problem, you are just seeing the symptoms. Some quick google results for premature plug wear:

There are other factors that can reduce plug life (all spark plugs eventually wear out; it’s just a question of when).

Overheating Damage: Overheating spark plugs can cause the electrode to wear faster. Pre-ignition from an improperly timed engine can cause this, as can an incorrect air to fuel ratio.

Oil Contamination: If oil seeps onto the spark plug, it will foul the tip. This creates damage and additional wear (oil seeping into the combustion chamber is something that happens over time as seals begin to fail).

Carbon: Carbon buildup on the tip can also cause premature failure. This can happen due to dirty injectors, a clogged air filter and many other reasons.