When carrying out diagnostic checks, it is essential to go back to basics – and it pays NOT to assume…
Kim Henson reports on another expensive mis-diagnosis…
Recently I wrote on this website about the necessity for taking great care when assessing what ‘stored’ automotive fault codes (i.e. those saved in the memory of the Electronic Control Unit or ECU) are telling the technician or vehicle owner. Often they will lead the operator to a general area within the vehicle’s electronic systems, but will not necessarily tell the whole story.
In addition it’s essential for the operator to know how to properly and fully analyse what the ECU and its fault codes are telling him/her. It is often the case that new components or even systems are installed due to fault codes that are misleading, or due to the operator misreading/misunderstanding them. This approach may or may not cure the actual fault (if it does, it is sometimes more by luck than judgement) but either way tends to be an expensive exercise for the vehicle’s owner.
So it was in the case recently brought to my attention by diagnostic specialist Edward Haggar, to whom I am grateful for passing on this cautionary tale. He had been called upon to check a VW Caddy that had been suffering from poor starting. The customer came to Edward after having spent £700 with a garage that had renewed the fuel pump and filters, but when the vehicle still refused to start they were at a loss regarding what to do next…
It didn’t take Edward long to carry out a full check of the vehicle, discovering early on that the diesel cooler and associated pipework beneath the vehicle had been severely damaged – presumably by major contact with the ground – and that one of the pipes was crushed almost completely flat. This caused a restrction that certainly wasn’t helping with fuel delivery…
With a replacement cooler and pipework installed, the van started and ran perfectly…
VERDICT
It pays to get a specialist diagnostic technician or firm to fully check a vehicle with a specific problem, starting with the basics, as in this instance. Be especially cautious if the non-specialist garage/mechanic you use advises renewing components ‘one by one’ until the problem goes away. (Of course, main dealers should also be able to give you an accurate and complete diagnosis, rather than simply renewing components – although we know this can still happen).
