QUESTION: I'd like your advice on something. My "check engine" light came on about a week ago. I took the car to the dealer and they said I'd need to do the 60,000 mile service before they could fix the "check engine" light problem. It's a bit over the mileage — 71,000, and dollars are just too tight right now to do more than an oil change and try to get the "check engine" light fixed. Is this right? Could the 60,000-mile service turn off that light?

—K.T.

ANSWER: Hmmm. Dollars must be tight for the dealer as well, if they need to resort to such upsell tactics. It's always a good idea to bring a vehicle up to current maintenance status prior to performing an engine performance diagnosis, but being hardnosed about it just isn't reasonable.

Let's say you have been feeling an occasional engine misfire, and the DTC (diagnostic trouble code) also points this way. If you were due for spark plug replacement, it would make perfect sense to do the maintenance first — with a little luck — fresh spark plugs would fix the check engine light. On the other hand, should the DTC point to a fault in the fuel vapor management system, changing the spark plugs or transmission fluid, or lubing the door latches certainly would have no effect.

Retrieving a DTC from a vehicle with an illuminated check engine light is a very quick and simple process using a scan tool. This could be a sophisticated model or a cheapie OBD-II scan tool, which costs less than $100 at the neighborhood auto-parts store. Once one obtains the code, a look through the code definition chart — or a quick Web search — will indicate the general fault area. The definition will read something like this: "P0446: Evaporative Emission Control System Vent Control Circuit Malfunction." While further diagnosis is clearly necessary (a skilled tech, following a diagnostic flow chart, using appropriate test equipment) one could safely assume the fault has nothing to do with pending maintenance.

It sounds like you threw it in reverse in the service driveway and that a DTC has not yet been obtained. Retrieving the code would be good way to proceed. Do you have a neighbor or friend with a cheapie scan tool? Many auto parts stores will retrieve the code for free, on the assumption you'll purchase any needed parts from them. In a few cases, such as the vent code above, one could roll the dice, forgoing further diagnosis, and simply renew the fairly inexpensive vent solenoid. In other cases, with a less specific fault description, or expensive parts, it's wise to do it right and continue with a professional diagnosis.

I won't scold you for being behind on maintenance. Do your best to keep up with what's most important, such as oil changes, and every six months on these will be fine. Timing belt replacement needs to be taken seriously as well. It is important to have a skilled set of eyes, ears, and nose give the car a periodic look-over for potential problems such as belts, hoses, fluid leakage, brake condition, etc. You'll sleep better knowing all is well, or what next to budget for.