Abstract: An automatic programmable cleaning system for heat transfer tubes in an engine exhaust gas waste heat recovery boiler is disclosed. The waste heat is transported as an exhaust gas stream at a water vaporizing temperature through heat transfer tubes in the waste heat recovery boiler. The automatic programmable cleaning system operates on predetermined cycles to inject water into the waste heat exhaust gas stream during the operation of the waste heat recovery boiler in order to vaporize the water injected into the waste heat exhaust gas stream and loosen carbon build-up in the heat transfer tubes. In this way, the loosened carbon and the waste heat gases are exhausted together from the waste heat recovery boiler during cleaning thereof. The method for automatically cleaning a waste heat recovery boiler including repetitive cyclical cleansing of the heat transferred tubes by injecting ans vaporizing water in the waste heat exhaust gas stream during operation of the waste heat recovery boiler is also disclosed.