Car has been running sweet since that engine code about a month ago, and after the battery drain issue of 3 weeks ago... that seemed to be an anomaly that I couldn't track back to anything. This morning I came out and tried to start the car to find it wouldn't start... there was juice in the battery just not enough to fire it up. Clock remains the correct time and radio stations are still stored... so it's not a dead battery and I had it tested a couple of weeks ago. I charged up the battery with my charger for about 10-15 mins and that was enough to get it started. Had a 25m trip to do and it performed perfectly fine... But as I was driving along I noticed the engine light was on. When I arrived I plugged the code reader in and got a P16A4 with $12 after it... but think that last bit is superflous. After reading the codes I reset it and it hasn't come back. So what is that code? I think that I'll replace the battery regardless of what the test said... the sudden cold snap we had this last few days could have had an effect on the battery and whilst it seems to be holding the right charge and seems to be charging correctly... last 2 weeks I've done nothing more than 2-3 miles trips with heating often on along with heated screens and mirrors. I'm away for a few days so don't have access to some of the stuff at home... is the P16A4 to do with the swirl valve again or is it something new... Cold weather could have caused the swirl valve to stick too I guess. Either way... it comes at an inopportune time. MOT is due in less than 3 weeks and I've not serviced it yet nor run the cataclean through the system... it's further expense I could do without... but I can't risk finding a flat battery at random like this.