Q: Car hesitates to start, and check engine light on

If the check engine light is on, that will possibly lead to an important clue as to what is going on. Typically, there will be stored OBD-II trouble code(s) when the check engine light comes on and those codes can be downloaded by the mechanic. Diagnostics can proceed on the basis of those codes. The codes are NOT the diagnostic itself but rather the codes will provide clues as to which vehicle components must be actually tested. To obtain a check engine light diagnostic, and a specific evaluation of the starting difficulty that you are writing in about, please request service via YourMechanic’s hard starting diagnostic service page. The responding certified mechanic will get this resolved for you. To give you some initial ideas, although there are many causes of hard starting illustrative causes include a faulty engine coolant temperature switch (sensor), malfunctioning idle air control (IAC) valve, vacuum and EGR leaks, inadequate fuel delivery or pressure (clogged fuel filter, injectors), and contaminated or old gasoline. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.