I have a 2003 passat v6 wagon 4motion (atq). I believe it is B5.5. It started intermittently not cranking. It also has a weird quirk. If it does crank it starts up fine cold and hot but if it is warm (like it sat 20-45 minutes after running) it cranks and takes a while but then starts. This has been consistent. Recently it switched to intermittently not cranking at all. All the other electric functions on the car seem to work, lights, radio etc. At first it would do this and intermittently I could start it. It ran and drove well when it started. Jump starting doesn’t seem to change anything. The battery is about 2 years old. Vag codes 17831 and 17819 are the only codes. Had vacuum line service this spring. Also new coilpacks, neutral safety switch replacement at the same time as a transmission maintenance. Ran well for several weeks after service then this started. Battery and CEL stay on after the dash light test. My battery tester in my charger said bad battery then tested good on second charge. Battery? Starter? Someone mentioned the engine ground?…. If I have a step by step guide I can do multimeter and other testing but I have no manual for this car. Love the car when it’s running.