Q: I replace the thermostat and was told to drive it for engine light to go out but its still on after 5 days what can i do?

Anytime a vehicle repair is performed to remedy faults that arise from a check engine light (CEL) diagnostic, at the conclusion of the repair, a professional mechanic uses an appropriate scan tool to turn OFF the check engine light. The purpose of that is to ensure that the repair(s) has the intended result which is to resolve all reported vehicle malfunctions. If after turning the CEL off, the light comes back on, that means the repair was not effective and/or additional faults exist. Diagnostic trouble codes invariably specify many, many possible "causes" insofar as a vehicle malfunction. The codes can NEVER be used to "automatically" condemn parts without further specific diagnostics and testing. If the thermostat, upon removal, did not test faulty, then that was not the cause of the trouble code. In addition, there could be multiple faults occurring even if a single code is reported and, of course, there could be multiple codes. Modern vehicles are complicated. Consequently, I encourage you to request a check engine light diagnostic and YourMechanic will dispatch a certified expert to read the Codes presently being reported and get the root cause of the fault diagnosed and repaired without further hassle on your part. Please let us know how we can best assist you to get this resolved.