Having somewhat of a similar concern. I am looking into a prospective buy, read the Lexus maintenance records. It says 4LO was flashing and there were the two codes P0441, P0456 INCORRECT PURGE FLOW AND SMALL LEAK DETECTED IN EVAP. Car was brought into dealership 4 times with the same problem, they ran smoke tests leak tests, gas cap replacement but couldn't clear it. Car was traded in by owner as a result. Next records indicate more work was done in the order 1. Crankshaft position sensor was replaced (which is strange since it is a P0335) 2. Charcoal cannister replaced and 3. Battery replaced Don't see a purge solenoid replacement. Any insights as to what could be happening here. Do you think the unit associated with EVAP is damaged? Any insight would be greatly appreciated.