A Marv in the palm of your hand

I once knew a mechanic named Marv. (Could there be a better name for a mechanic? Picture him: Brylcreemed black hair combed back in a bit of a pompadour; grey trousers and shirt with “Marv” on a shoulder patch, oil-stained loafers, and perfect white socks. That’s Marv.)

Marv had a shop in which he built hot rods for fun while doing ordinary mechanical work to pay bills. He had the contract to maintain J.C. Penney’s furniture-delivery trucks when I was driving them after high school.

The thing about Marv was, vehicles talked to him. I don’t think I ever saw him have to do more than listen to a truck or car for a few seconds before perfectly diagnosing its issue. “Throwout bearing,” he said into my window when I pulled up in a truck that was making a strange noise during shifts—before I even parked or mentioned the specific complaint. “Front U-joint,” “Water pump,” “Burned exhaust valve”—those are Marv diagnoses off the top of my memory. I once brought in a truck that had started running rough, and he said, “The timing’s slipped.” Did he go fetch his timing light? Nope—he pulled out a half-inch wrench, loosened the nut on the V8’s distributor, turned it with his head cocked to the side, revved it a couple of times, tightened the nut, and said, “There you go.” That time, one of my co-drivers (Vern—could there be a better name for a furniture-delivery man?) was with me. He knew Marv well, but not well enough. 

“What’s the timing supposed to be?” Vern asked. 

“About seven degrees before top dead center.”

“And how close do you think you got to that?”

Marv said nothing, just fetched his timing light and, well, I bet you can guess the rest by this point. Some time after that I was summarily fired for rapelling off the J.C. Penney warehouse roof (just for fun—a story for another time), and I lost track of Marv and his preternatural skill.

Today? Today any rookie with 20 bucks, an Amazon account, and a smart phone can enjoy a near-Marv-like mind-meld with an OBDII-equipped vehicle two days after clicking “Add to cart.” I know, because I finally ordered a KingMansion ELM 327 wi-fi-enabled OBDII reader that sends all sorts of interesting and useful information to my iPhone, including stuff even Marv couldn’t have determined (although I doubt it could identify a faulty throwout bearing). The only catch is, you’ll also need a compatible app for the phone—cheap if you buy something like the $10 OBD Fusion in the iTunes app store, more expensive if, like me, you don’t pay attention and wind up with one that also synchs with the phone’s accelerometer to record 0-to-60, G-force, and lap times. If I ever decide to try for a new Tacoma/Four-Wheel-Camper lap record at Riverside, I’m all set.

In case you don’t pay attention to such things, OBDII (for On Board Diagnostics) is a standardized system and port (in the U.S.), mandatory on all passenger vehicles since 1996. It allows the vehicle’s CPU (central processing unit) to communicate information about the engine’s emissions (the original intent), instantaneous fuel usage, actual engine temperature, engine load, air intake temperature, and much more, depending on what the vehicle’s manufacturer chooses to make available.

Most useful for owners, however, is the ability to read trouble codes when the dashboard energizes that annoying and oh-so-vague “Check engine” light, which could indicate anything from imminent disaster to something utterly harmless such as a failed reverse lockout switch (this happened on our old Tacoma). 

I followed the instructions on the absurdly inconsequential-looking ELM, and within minutes the Tacoma was assuring me all was well fault-code-wise. Other functions such as instantaneous fuel mileage (full throttle in first gear with a camper = 7.142 mpg) also popped up and worked perfectly.

If you do hook up an OBD scanner in response to the check-engine light, don’t expect a little pompadoured Marv to pop up on the screen and tell you what’s wrong and how to fix it. All you’re going to see is an alphanumeric code (or perhaps several). You need a guide to tell you which of a mind-boggling array of faults you are experiencing. It might be, say, code P0812, indicating a reverse switch malfunction, which you can ignore if you’re in the middle of nowhere, or, say, P0304, indicating a misfire in cylinder four, which you would not want to ignore. Codes that begin with a P0, P2, or P3 are universal codes; those that begin with P1 are manufacturer-specific. Many websites have been created solely to list and explain OBDII codes. (Toyota has a professional site here that caters mostly to mechanics, but you can apparently buy a temporary subscription to retrieve current technical bulletins and OBD codes. I write “apparently” because it’s only compatible with PCs—and only using Internet Explorer, for God’s sake. C’mon, Toyota.)

By far the most likely scenario is that even after you look up the code you’ll be presented with some utterly incomprehensible diagnosis, such as P0608, “Control Module VSS output A malfunction.” The reason for this is that, when the people in charge were programming what the standardized OBDII sensor would monitor and flag, they decided they wanted it to be the equivalent of the most hypochondriac human being on the planet—just to be safe, and to give car dealers plenty of work. So—I have no proof of this yet, but I’ll get to the bottom of it—I’m virtually certain they kidnapped my mother, hooked up electrodes to her in a secret research facility in Detroit, and remarked admiringly, “Wow—we need at least 360 potential fault codes.”

Whatever the case, you’ll have to decide whether one of these obscure codes is reason to abandon a trip and head to a mechanic. My own reaction, if the truck were running well with no outward signs of trouble, would probably be to mutter, “Yes, mom, whatever you say,” and keep right on driving.