If your fuel consumption is increasing it would be worth considering if worn out or failing components are responsible before looking at engine cleaning. Blocked injectors, turbo issues, dirty air or fuel filters or EGR problems can all contribute to increased fuel consumption. Engine cleaning services usually focus on either the fuel system, the air intake or the DPF (if fitted) which can become affected by carbon or other deposits. The quality of the results may vary and we would recommend using a respected specialist, but any improvement would be slight if there are other issues.