Dear Car Talk:

I have a 2010 Smart Car. The Check Engine light would not stay off. I took it to the dealer before the warranty expired. They found nothing wrong and told me I probably had a bad tank of gas, and that I should wait for it to get used up and fill it with "good gas" next time. I did that, and sure enough, the light went off. But a few weeks later, the light was back on. The same thing happened -- new tank of gas, light goes off, then comes back on. This scenario was repeated several times (sporadically, not with every tank) until finally the light stayed on permanently.

Of course, by then it was no longer under warranty. So the dealer "switched sensors" to see what that would do. I didn't even make it home before the light was back on. This time, they said they would come and get it (I live 45 minutes away) and bring me a loaner. A day later, they told me I need a cylinder head because I have a leaking valve, and it will cost $3,400. The guy said that, since I have less than 10,000 miles on the car and I'd brought the problem to their attention while it was still under warranty, he'd already contacted the district manager, who agreed to cover all but $500, which I am to pay. Is this a good deal or not? In my opinion, they should cover all of it. Thanks.

-- Mary

Car Talk: I agree with you completely. This clearly was a manufacturing defect. The engine failed at less than 10,000 miles -- that's ridiculous. And you brought the defect to their attention while the car was still under warranty. What possible justification do they have for charging you $500? The whole thing's on them. If they had figured it out the first time you took it to them, it would have been under warranty, and there would be no $500 charge. So they're billing you for their ineptness in taking months to figure out what was wrong.

I do think it was nice of them to come and pick up your car after the second time they failed to solve the problem. That, at least, allowed you to avoid the terror of driving this chamber pot for an additional 45 minutes. In billing you for $500, I think they're launching what we call a "trial balloon," Mary. They want to see if you'll roll over and give them the money.

Don't do it. Remind them that the defect was reported to them during the warranty period, and that you have that in writing (the service slip). And ask them what possible justification they have for charging you at all for a warranty repair. If they don't say, "Yeah, you're right, Mary," mention your state's attorney general's office, and suggest that you're going to call to get their opinion before authorizing the repair.

Or do what my brother would have done, and just keep the loaner! And by the way, pretty much whenever a mechanic says that your problem is "bad gas," that means he couldn't figure out what's wrong, or didn't want to take the time to figure it out. Or he's upset that you have bad gas and are stinking up his waiting room.