Freelander struggling to start when warm

Hi,

Newbie here, my freelander is struggling to start when the engine is warm. Sometimes it doesn't start at all. Plugged it in to check for fault codes and got the following fault show "low side fuel pressure sensor plausibility" the bloke at the garage said a it could be the fuel sensor. I ordered a second hand fuel rail of eBay and hope the sensor is good on that. Any other ideas to what it could be if this don't work. Also is it easy to replace the fuel rail ? I am not use to working on cars but would like to get use to it. Any help would be appreciated. Cheers Jamie