I am searching for patents similar to my product. Is performing a search on google patents using CPC adequate to find prioir art? If i do not find patents similar to my product in the search result, is it safe to assume that there is a high probability of patenting my product?
No. As mentioned in a comment, patents and patent publications are not the only sources of prior art. Professional technical journals, magazine articles, books and even youtube videos could contain relevant prior art. Also, CPC is a joint program of the U.S. and the EPO. Patent documents from other locations may not even have a CPC classification. To get a US patent, for example, the claims must be novel and non-obvious over everything ever published anywhere. Not just in relation to US patents.
Most DIY patent searches only use keywords where professional searchers tend to use both keywords and classification searches. Only using classification searching could miss something that is mis-classified and the boundaries between classes can sometimes be obscure or otherwise misunderstood by the searcher. After getting close with these searches, it can then pay off to follow forward and backward citations from the things you found that seem the closest.
Last, it is almost unheard of to not find things "similar to your product". If you do not find anything similar, you have most likely not yet done an adequate search.