10 March 2003
Conspiracy theory behind the dash
Americans have lots of thoughts about things automotive. (This is, in case you've forgotten or you've been living in Berkeley for the last ten years, because we actually have lots of cars and we get to drive them all over the place.) Inevitably, some of those thoughts prove to be erroneous, egregious, or downright excruciating (cf. an otherwise perfectly innocuous Honda Civic with two-thirds of its bodywork covered in bubbly decalcomania and its exhaust terminating in a Folger's can).
There is one thought which borders on the universal, though: the thought that the so-called Check Engine Light is a conspiracy against the laity, that the evil little glow means only that your local wrenchman has a boat payment due. At least once a week, I get an anguished letter from some poor soul asking how to shut the thing off, and I'm running out of variations on ways to say "Take it to the shop and have the farging codes pulled."
The truth of the matter is simply this: modern engines run with extremely tight calibrations to meet extremely tight (and becoming more so) emissions specifications, and if any one component of the twenty bazillion or so under the hood isn't pulling its weight, the Malfunction Indicator Light (to give it its correct name) snaps on and the engine computer records the appropriate error code. Unless you know what that error code is and what it means and I, buried in email, certainly can't read it from here you're out of luck. And present-day OBD II-equipped vehicles don't give up their codes to just anyone: you need the appropriate scan tool.
Which, of course, is part of the conspiracy. If you don't want to pay the dealer $75 to pull the codes, you probably also don't want to pay hundreds of dollars for your very own scanning device. But the unpleasant fact is this: the shadetree mechanic is well on his way to dropping off the Endangered Species list and into extinction. The techniques that used to work to squeeze a couple more months out of a worn set of points don't mean a thing to a mass airflow meter. And given the fact that most people think they're more mechanically inclined than they really are myself included twelve or thirteen times out of ten they're going to make matters worse by trying to fix these things themselves.
Please. Take it to the shop and have the farging codes pulled.