Dear Tom and Ray: We recently took our 2001 VW Jetta to the dealer because the Check Engine light was on. After guessing at the solution (something about the code was vague), they charged us 280 dollars for diagnostics and to replace the air filter and spark plugs. They also wanted 65 dollars to run a "post-repair diagnostic check"; I refused, as it seems to me this should be part of any repair. They prominently noted my refusal on the repair bill. We picked up the car after the repair shop had closed. The Check Engine light was still on, and the car ran worse than before. The next morning, they wanted to charge us 118 dollars for another diagnostic. I would have ranted and raved, but my saintly wife used guile to get them to back off. So my question is, Should I ever pay for a "post-repair diagnostic," or is this just a pure rip-off?

-- Craig

RAY: Our customers do our post-repair diagnostics for us, Craig. They drive out of the garage, and if we see a wheel fall off, then we know we didn't fix it.

TOM: You did the same thing, Craig. And I'd have to agree with you, that determining whether you fixed the problem is part of the repair process. So that's not a reasonable charge.

RAY: My guess is that they scanned the car's computer and got a vague code, like "engine misfire." That doesn't always tell you exactly what's wrong. It gives you a good clue about where to look, but often you have to take it from there.

TOM: So they took a reasonable guess with the spark plugs (not sure about the air filter -- maybe they were having a special?), but the spark plugs didn't fix it. What they should have done next is take out the spark plugs (unless you clearly needed new ones anyway), take them off your bill and start trying some other things, like coils, plug wires or a crank angle sensor.

RAY: If we had been working on your car, that's what we would have done (after we sold you a rug shampoo and a platinum-tipped pine-tree air freshener). And IF we eventually fixed the car, we would have charged you for 100 percent of the diagnostic time, because that was time we spent making educated guesses, installing and removing parts, and trying to solve your problem. That's only fair.

TOM: But we would have charged you only for the actual parts that fixed the car. The rest would have gone back on the shelf.

RAY: If you want to put this in the best possible light, Craig, maybe these guys were heading in that same direction. Maybe they're just guilty of having an awful presentation.

TOM: I doubt it. I think they were trying to overcharge him. They didn't solve the problem, and they needed to do more diagnostic work. But they should have just said that, and offered to take back any unnecessary parts. They need to learn that honesty is always the best policy.

RAY: Right. Especially once you get caught.