Error code 5 relates to a pair of resistors on the side of the injection pump, at least on the 2.4TD engine. These resistors are installed when the pump is calibrated and fine tune the timing and fuelling. I measured both resistors. The grey one was 0.622kΩ while the beige one was open circuit. The insides are potted in epoxy, so I dug out the trusty Dremel and went in.