02 focus 1.8tdci fault code p2337

[leetrials]

Hi was hoping someone could help me. My mondeo st died about 5 weeks ago so bought this focus while I fix it. Has run great yesterday the glow plug light started to flash and lost power into limp mode it's hardly starting from cold and misses and smokes while running. I've run forscan on it and got the code

p2337 cylinder 2 above knock threshold.

Explanation of this is in short could need recoding or replacement.

I am going to try recoding first but while using forscan today I went into the set up and all the correction factors are set to zero is this right?

Also what order are they to be saved in? 

And lastly which code do I need exactly?

Or if anyone knows of any other causes this could be I'd appreciate it I need to get this running again by Monday latest :/

Thanks Lee.