I don’t think check engine light performs well on all situations. Yes it true that many engine issues can be rectified with the help of this small light but sometimes its turn-on irritates a lot especially when there is not any problem in system. In this case, I fully agree with Rob, you should buy another headlight from any dealer like http://www.iautobodyparts.com/exterior_lighting-catalog/ or other and replace it to check whether the check engine light turns off or not. No other idea seems better than this, hence I think you should go for it.