Good morning all, Over the last few months my 2005 A6 C6 3.0 TDi has developed a hot start issue. When it has been on a good run and is nice and warm, it will refuse to fire. It is now happening more than once a week! It will always crank perfectly, for exactly the same amount of time (about 3-4 seconds), and seemingly fast enough as well. But it wont fire at all. Being a diesel, the only thing stopping it from running can be fuel. So far, every time it has done this, I've left it for about 10 minutes, and then its started perfectly. I've scanned it with VCDS a few times and seen no codes (both after the fact, and while I was trying to get it to start). I expect the ECU will be making a number of checks while the engine is cranking, Presumably fuel pressure, certain pressure switches and other parameters in the engine, maybe also the immobilizer as well? But I don't know what the conditions are that need to be met, or how to check them. The last time it happened (Last night in a services in north wales!) I had my laptop with me, so tried to log a couple of things in VCDS, but I wasn't really sure what to log. I logged fuel pressure while cranking, the first time I tried it, it got to 96Bar, which seems a little low, but the second time it got to just below 300Bar and still didn't start. I then went and popped the fuel return off and put it into a mug while my GF turned it over, there was indeed fuel coming out, and it started! So we had to stop it and put the return on, and then drove the rest of the way home. When it first happened a few months ago, I knew I also had the normal injector issues, so I put it down to excessive injector leakage preventing fuel pressure buildup. But they have now all been replaced with Rev AH injectors which aren't leaking (no smoke now and correction factors have settled at sensible values), so I've ruled that out in my head. Does anyone else have any ideas? I can keep my tools and laptop in the boot so I can investigate it next time it happens. I really need to get to the bottom of this! Cheers all!