EJ20X throwing P0340, stalling and wont restart when warm.

[jdgreaves67]

Hi, I hope everyone is well! 

I recently bought a 2007 Jap Import Legacy BL5 GT Spec B with the EJ20X (auto) powertrain to replace my UK legacy BP EJ204. 

Took the BL for a great and long test drive with the previous owner and all was well, drove fantastically, pulls well and super smooth! 

The day I collected it, a few miles down the road (just as it got fully up to temp) it cut out on me and didn't want to restart. Managed to get it going in short intervals but any kind of load introduced caused it to stall again. 

Got the car recovered and when on my drive used my code reader to pull P0340 - "camshaft position sensor A circuit bank 1 or single sensor". 

I know there can be a range of reasons this comes up but being hopeful I ordered a replacement sensor (while they're fairly cheap) in the hopes that it was a simple sensor failure. 

As I understand it, bank 1 in the UK drivers side and sensor A would be the 'first' sensor, i.e. intake? Being an EJ20X it does have 4 cam sensors in total for the variable intake and exhaust cams. 

I replaced the sensor as described and it started up beautifully. Took it for a short run on Sunday which was fine so decided to brave my commute on Monday. 

I have a 9 mile commute and bought myself on a route to avoid any motorways (should it break down again). Just as I was mid-turn into the road I work on, it cut out on me again and didn't want to start - checked with my reader and it was throwing the same P0340.

I went into work for the day expecting that I would need to have the car recovered when I finished; to my surprise, when I finished work it started up beautifully again so I decided to risk the drive home. Drove gently and carefully but the car was smooth as silk all the way home, but I'm of course confident that at some point the code will be thrown again and the car will stall on me - it seems to be when it gets fully up to temp. 

I've checked the connections and wiring as best I can without dismantling anything and they all seem (much like the rest of the car) very clean, however I've still given them a clean with contact cleaner just in case.

The only thing that had changed recently on the car (to the best of my knowledge) is a new Battery. On inspection, after the first time it stalled, I found the negative terminal to be loose (could be slid off by hand). Thinking this might be the issue at the side of the road myself and a friend loosened the strap, fit a screw in between and re-tightened to ensure a tight contact - I have since remedied this properly with a new properly fitting negative terminal but I'm wondering if this could have been the cause of the issue as I know the system is very sensitive to changes in voltage? 

My plan for this afternoon/tomorrow (weather permitting) is to check and recheck any wiring/connections I can physically see, run the car up to temp on the drive and then see if I can drive it any distance at full temp but any other suggestions would be very much appreciated from anyone who's experienced a similar issue - this has of course taken the shine off the car I was very excited to own but I'm sure it'll be worth it once repaired. 

Thanks in advance for any help/advice! 

Regards

John