Hi, vauxhall astra mk4 2.0 16v dti, having real trouble getting it started!?

Hi, vauxhall astra mk4 2.0 16v dti, having real trouble getting it started!?

i have put new glowplugs on to rule that out! Also when the engine is cold it runs fine! As soon as it is warm a warning light comes on putting the car in ”limp mode” it will stay on untill engine is cold again, but then i have the prob of starting it! I know i need to fault code it but was just wondering if any1 knows what it might be? Im stuck now! Thanks for taking time to read!