What's the best cleaning products for diesel engines?

The emissions warning light is illuminated on my BMW 5 Series diesel. My local garage has said it is due to carbon deposits in the manifold and wants more than £2000 to clean it. Can I do it myself? I was thinking of using cleaning fluid such as Archoil AR6400 added to the diesel tank and/or then using a premium diesel which claims to have cleaning properties.
Shell V-Power Nitro Plus will remove some hydrocarbon deposits but is not a liquid decoke. You might be a customer for www.terraclean.co.uk/ Ed China is behind it, but I don't have enough feedback to make a positive recommendation.
Answered by Honest John on

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