Long Start Issue

Hi guys just thought I'd post this on here in hopes of getting some ideas on the long start I'm having with my fabia.

I've been having this issue a long time now which came on one day suddenly. When starting up, it takes about 3 seconds of cranking before the engine starts. Last time I checked with VCDS I got a camshaft position sensor signal implausible (I think) error, so since then I've replaced the camshaft position sensor still the same issue. I've then replaced the crankshaft sensor, checked the wiring from both sensors to the ecu for continuity and they check out okay. So I'm currently a bit stumped.

Any ideas would be greatly appreciated, thanks!