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Mike Kelly
Mike Kelly, Auto Service Technician
Category: Car
Satisfied Customers: 5471
Experience:  17 years experience as an auto mechanic, foreign and domestic. 5 years running my own repair business.
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I have a 2001 VW Sharan 1.9l diesel car which has been slowly

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I have a 2001 VW Sharan 1.9l diesel car which has been slowly losing power over the past few years and is now becoming seriously slow!

There are no fault codes on the ECU. Is it possible that the oxidation catalyst has become blocked with soot and, if so, can one clean the thing? Many thanks!
Hi,my name is XXXXX XXXXX I will assist you with your question.
The issue that you are having and the way it has progressed over time is in fact consistent with the catalytic converter becoming restricted cutting off the air flow. Technically the converter can be cleaned However the issue normally returns as it is not possible to get it fully clean. The best option is to replace the converter.
Customer: replied 4 years ago.

OK, thanks Mike. I'll get the catalyst changed to see if that fixes the problem. If it doesn't, do you have any other ideas of what to investigate next?

I believe this will cure the issue but if it does not I would have the fuel pressure checked and the throttle body checked for carbon build up.
Customer: replied 4 years ago.

OK, thanks for these ideas. The fuel pressure may well be worth checking if the catalyst change does not work. However the Sharan does not have a throttle body - it uses unit injectors - I suppose that the nozzle tips on these may have become partially blocked with carbon deposits over time, but I think that servicing unit injectors is a major job - my VW main dealer wanted £2K for a new set!

Yes it is a big job and expensive. There is a fuel induction service that can be performed without removing the injectors this service is performed by a special machine found at most shops. It's basically a solvent that is ran through the fuel system that cleans the entire system.
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