Sounds like you have heater plug problems,at front of engine and the EGR valve needs removing for access,any doubt replace the lot. Also worth checking would be the maxi fuse for the plugs in the fuse box at bulkhead just above the battery,you don't say why you think it is your flywheel but I think crank sensors on these is quite a common problem,good luck.
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Try fixfault.com to fix vans.