Strange issue with my CLK today. Headed off to work and car started fine, then 2 minutes up the road, I remembered that I'd forgotten something so headed back home. Pulled up outside and ran in the house to grab what I needed (was in the house all of 2 minutes) and then came back out, jumped in the car, and now I just get this noise of presumably the starter motor trying to start the engine, but doesn't actually crank. I have an ELM327 WiFi OBDII gizmo and an app on my phone called "FourStroke" which pulls up the error codes on the car, and I'm getting a P0112 error code. Feel like I'm going down the rabbit hole with this one as so far from looking on google, from what I can tell it could be the MAF sensor, the CPS, the fuel pump or an electrical fault! :-( What's making me think that maybe it's not the CPS is that it doesn't start regardless of whether the engine is hot or cold, and I've read that normally if the CPS is faulty, it will normally work if you let it cool down for half an hour or so. It makes no difference and still won't start even after leaving the car for two hours. What's making me think its' not the MAF sensor, is that most people say a MAF issue really affects vehicle performance, but won't stop the car from actually starting. I guess it could be the fuel pump, but wouldn't that bring up a different fault code? I can clear the P0112 code with the app, then turn the key, hear the noise and the error code comes straight back again. I checked the fuse in the boot for the fuel pump and that looks fine. I also swapped the relay for another identical one I borrowed from the fuse board under the bonnet (Hella 12v 4RA 002 542 26 19) that does another job, but that still didn't work so doubt it's that. I uploaded a quick video of the noise (unfortunately the sound isn't great - Also please ignore the 3-4 "dunk" noises at the start of the video as that's an unrelated issue of a plastic cog hidden away behind the dash that controls air-con direction...apparently a common fault on the CLK's) YouTube clip of car not starting What do you guys think? What I'm thinking I'll do is firstly change the CPS (this one) and if that doesn't work, then change the MAF (this one) and either of those don't work then possibly a new fuel pump? Any help/advice would be much appreciated!