Why are Piezo injectors failing in Volkswagen Group TDI engines?

We are noticing a very expensive trend of Piezo injector failures on Volkswagen Group TDI engines and, at around £500 a pop, this is not funny. Also recommended is a new associated wiring loom due to it going brittle. This sounds like a poor design, or designed to fail just out of warranty. I found the data on SEAT, Golf and Skoda web sites.

Asked on 6 July 2010 by K A Young [oldoiler]

Answered by Honest John
It's happening on Mercedes-Benz cars quite a lot too. It seems to be a problem with the parts, which I think are manufactured in Malaysia. They have a very fine production tolerance that may be impossible to achieve with 100 per cent of production. Ford will not touch Piezo injectors.
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