Gonna share my recent experiences on here as I've used this site several times to fix my various Volvo's over the years , and may be of help to others. if anyone has anything to add regarding my recent problem and what was actually wrong with the car, please feel free

I have a 2003 V70 D5 diesel which recently developed a non start problem, car would crank but not fire up.
Initially I purchased a brand new battery, fitted ,and car started straight away, I then drove for 2 days with no issues
On the 3rd day ,the car would not start at all, with new battery along with a fully charges battery attached together with new one. Car was running excellent prior to this with no errors/ warnings/ misfires etc

I could hear LP fuel pump priming on ignition, I'd had a new starter fitted approx 6 months ago, but removed and tested just to be sure, all good.
I removed fuel line after HP pump/ prior to rail, and had fuel at this point.

Next step was the crank sensor, so I purchased an aftermarket CS only to find either/and ..1. what I thought was my crank sensor was a different size with bigger diameter ,or what I thought was my crank sensor was not in fact the crank sensor and therefore had/still have no idea where the crank sensor is positioned on this model ??
...2. what i thought was my crank sensor was also connected to my Cam sensor which where joined together by 1x connector box rather than a separate box for each sensor, these where connected to the front of the vehicle next to the L/h headlights. Sensors themselves are positioned 1 on top of auto box to front of vehicle and 1 to rear of engine underneath air intake pipe and as previously stated, look as though they are 1 x item (2 sensors joined in 1 x box), therefore no new CS was fitted.

I'd also purchased an aftermarket fuel pressure sensor, so gave this a try only to find that the thread gauge was a different size , and rather than try and force the sensor into the rail and risk damaging the rail, I instead decided to put the old sensor back on and call it a day.

I gave the car one last try and surprise surprise it fired up straight away, no error codes, no warning lights, all running excellent with no misfires etc ,2 days in atm.
My initial thought is that the car had become gassed up, and when I'd removed the pressure sensor I'd also released some pressure from the rails, possibly giving a correct reading to the pressure sensor ??

My next step is get the vehicle scanned again for saved codes and try to determine what exactly the issue was in case it happens again, but if anyone has any ideas in the meantime please add response
Also if anyone can tell me where the Crank sensor is positioned on this model please reply, as I still have no idea whether or not its joined with the cam sensor and both are sold as 1 unit rather than 2 x separate sensors , I can only find 2 types for sale, 1 with cable, 1 with no cable.