Do you mean that someone is trying to tell you that you need to CLEAN the electronic throttle module (ETM)? If so, it'll be a waste of your money.
Volvo USE TO have a TSB about cleaning them (first) but has since changed their minds on the idea as these cars would just come back with the same problems. If it's bad (with symtoms) and usually a CEL, the code(s) usually say "internal ETM fault" which means that it has internal circuitry problems, NOT a problem due to residue on the throttle butterfly, which I've never seen to be a real problem.