Had a look at this today (its my son's car)
Turns out it was the coil pack, it was obvious to me the car was intermittently running on 3 cylinders which would cause the 0314 error. With lots of unburnt fuel in the exhaust that's why lambda / O2 sensor errors were also being seen
I changed the coil pack and leads and also the air filter
The inlet manifold had a fair bit of oil in it which I cleaned up with some kitchen roll, not sure if this is normal on a high mileage (130k) engine. It does use a bit of oil but I'm expecting it to burn a little at this age so not unduly concerned
I wanted to change the spark plugs but could only get 2 out. I have the proper tool and 1 and 3 easily came out however the others I couldn't get the socket down onto the hex part of the plug. With a screwdriver I could feel some sort of obstruction, almost if a gasket or seal was swollen and stopping the socket bottoming out. Any ideas anyone ? Luckily the plugs aren't that old and the 2 that did come out looked in excellent condition so hopefully the same is the case with the others.
We're only nursing the car along hopefully until the MOT in August as there's a fair bit wrong elsewhere, the n/s/r wheel bearing is very noisy, the airbag light is on and probably all sorts of other faults
I finally reset the EML with my phone so we'll see how it goes from here.