Q. My car has over 80K miles on it and I’ve never had any trouble with it. But in the last six months I’ve had to do a couple of repairs that have cost almost $1000. Now the dealership is telling me that it needs another big repair. I’m wondering if the car is going bad. Should I trade it in?
A. This is our favorite question. As we say on our Mission page, cars are fairly well made these days, and rarely need much work before they get up to 70-80K miles. But repairs do start to come due then—normal repairs, that don’t mean you have a bad car. It can seem jarring to have to spend money on the car when you haven’t had to spend much before, but compared to the cost of a new car, it’s usually well worth it. The key is to take your car to a mechanic you can trust to tell you what’s really a necessary repair and what can wait a while.
One last point: this assumes you basically LIKE your car. If for some reason you DISLIKE your car—and gut feelings have their place with cars as with anything—the time to trade it in is definitely around 75K miles, before repairs come due.
Q. I’ve been taking my car to the dealer for service ever since I bought it. I know their check-ups are over-priced, but when I should stop going there? And can an independent shop know my car as well as the dealer?
A. The main answer to this question is that you should never go to the dealer for routine maintenance. We feel bad for dealers—they have to do all the warranty work on their cars, and the manufacturers don’t pay them full price for that. But the result is that they overcharge incredibly for their 30, 60, 90K check-ups. And any independent mechanic with experience knows how to check the basic things they check in these services—we even get to know the tendencies of the more popular models.
If you have a problem with one of the computer-controlled systems that is NOT the engine on a foreign car—say, the climate control system on a Mercedes or the air bag system on a Volvo—that is trickier. All the manufacturers have to release the software necessary to communicate with their engine computers, but some are stingy with the software for their other computer systems. There are some good independent shops that specialize in different models, though, and have invested in the same tools as the dealer has. Call us for recommendations.
Q. My ‘check engine’ light just came on. Can I keep driving?
A. The short answer is that yes, you can, as long as the light is on steady. If the light is flashing, you shouldn’t drive far, especially at highway speed, just a few miles to home or to a garage.
To explain further, the ‘check engine’ light comes on whenever the engine computer sees a problem with one of literally hundreds of things it keeps an eye on. The vast majority of these are things that make a small difference in pollution control, in the efficiency with which the engine runs (add up these small differences and you get the relatively clean cars we have today). Other than turning the light on, the computer is programmed to work around these smaller problems—it will keep the car running smoothly so you may not notice any change in performance.
But if the problem is more serious, the computer will flash the ‘check engine’ light. When this happens, you should get it checked right away, because the engine is probably misfiring in a way that allows the raw fuel injected into one or more cylinders to flow unburned into the exhaust, into the catalytic converter. And the converter may then glow red hot and eventually melt, adding extra expense.
Q. My owner’s manual says that the ‘check engine’ light sometimes has to do with the gas cap. What’s that all about?
A. Mishandling the gas cap is the most common cause of the ‘check engine’ light coming on. There are two rules to follow regarding the gas cap.
- Never leave the key on when you remove the gas cap to fill up.
- After filling up, be sure to tighten the gas cap until it clicks.
You may ask why these rules. Gasoline is pumped into your tank as a liquid, but as it sits there, some of it turns into a vapor. Have you ever noticed that when you remove the gas cap, sometimes there’s a whoosh of pressure being released? The government doesn’t want that pressure to be released except when you have to, at the gas pump. The rest of the time, the gas tank is kept under pressure—the fuel vapors are actually stored and then sucked back into the engine to be burned. And the computer actually has a way of checking that there are no leaks of fuel vapors from the tank—if the cap is loose, it turns the ‘check engine’ light on.
Q. My car is up for its annual state inspection and my ‘check engine’ light is on. Do I have to fix it?
A. If your car is under 15 years old, yes. As of October, 2008, there is no more tailpipe emissions testing in Massachusetts—the entire emissions inspection happens by connecting to the engine computer and looking whether it has spotted any problems and turned the ‘check engine’ light on. You have to resolve any such problems and make the light stay off before you can pass inspection.
But if your car is 15 years old or more—say, a 2005 vehicle in 2020—you don’t have to worry about emissions testing any more. They won’t pay any attention to the check engine light—you simply have to pass the safety inspection.
Q. Why can’t I simply have the ‘check engine’ light erased and then go for inspection before it comes back on?
A. They’ve thought of this trick. After the ‘check engine’ light is erased, you have to drive the car for two to three days before the engine computer will tell the inspection computer that things are OK. If you go earlier, the engine computer will not have completed certain monitoring tests that it has to run through before it can say that your engine is running well. And during these three days, you have to do a little highway, a little city driving each day—you have to let the engine fully warm up on your drives and then fully cool down at night.