Press Releases

Click and Clack Talk Cars

Tom and Ray Magliozzi
Saturday December 08, 2001

The ‘check engine’ light  

actually means something 



Dear Tom and Ray: 


I have a 1996 Oldsmobile 88 with 66,000 miles on it. At about 50,000 miles, the "check engine" light came on and stayed on until I took it to the dealer. $58 later, they told me the problem was a loose gas cap. They turned out the light, but it came on again about 5,000 miles later. Not wanting to be their cash cow, I ignored it, and it went out on its own a week or two later. Last week, it came on again for a few days and then went off. I hate to make these $58 trips, but am I damaging anything by ignoring this “on and off” problem? – Morry 



RAY: Well, you might be damaging the environment, Morry, if not your car. 

TOM: The "check engine" light comes on when one of the car's electronic sensors detects a problem. And most of the sensors are related to the car's pollution-control system. 

RAY: There are a few “check engine” problems that could cause expensive damage if you don't fix them, but many are non-emergency items and can be taken care of at your earliest convenience. 

TOM: For $58, your mechanic “scanned” your car (read the stored trouble codes in the computer) and found that the pressure sensor in the gas tank was indicating low pressure. The reason this is a problem is because it indicates that gasoline vapors are escaping. And a loose gas cap could cause that. 

RAY: Needless to say, seeping gasoline vapors are bad for the environment -- and bad for anybody who happens to be lighting up a Tiparillo near the back end of your car. 

TOM: So here's what I'd do next, Morry. I'd take another shot at the gas cap. Maybe it's loose because it has a bad seal. So get a new one. It costs $10 if you buy one. Less if you steal one. And it's worth a try. 

RAY: If the light continues to come on, then you need to scrape up another 58 bucks and have your car scanned again. The "check engine" light could be coming on for a completely different reason this time. And you won't know that unless you plug it into the computer and scan it. 

TOM: If it's still pointing to a pressure problem in the gas tank, then it's probably a leak in your evaporative emissions system. And your mechanic will have to address that. Good luck, Morry.  

Terminal help 


Dear Tom and Ray: 


In the 1950s and '60s, I spent a fair amount of time in Ford V-8s with my friend Herb Johnson. When one of these Fords wouldn't start because of a low battery combined with a Minnesota winter morning, Herb would fetch a 50-cent piece from his pocket, reach under the dash and touch it across two terminals on something. This would cause the engine to start. Which terminals were involved? Why did this work? I always wondered, but I had too much pride to ask. I secretly hoped that he thought I knew how to do the same thing. -- John 

TOM: You know, every woman reading this column today is shaking her head right now in sad recognition. You've been wondering for 50 years because you were too damn proud to ask. 

RAY: So let this be a lesson to the young men in our audience today. Never keep quiet in the face of unknown phenomena. Show some courage. If you see something you don't understand, don't keep quiet. Immediately accuse your friend of ruining the thing. That way, he'll be forced to explain to you what he's doing, while you maintain your all-important male dignity. 

TOM: I don't think old Herb was doing much of anything, John. He was basically hot-wiring the car. In the '50s and into the early '60s, most ignition switches were on the dashboard. If you reached behind the dash, you could touch the exposed wires of the ignition switch. And if you knew what you were doing, you could identify the solenoid wire and the hot wire, and could bridge them to engage the starter. You'd still need the key in the "run" position for the car to actually start, but I assume Herb had the key. 

RAY: Why he reached behind the lock and jumped the wires instead of turning the key to the "crank" position, I don't know. It doesn't make any sense to me, and I can't think of any advantage it offers. 

TOM: Maybe his key would get stuck in the cold weather and wouldn't turn to the crank position? 

RAY: Maybe this gimmick was an old myth his father had passed down to him, and he was too proud to ask his father why he did it? 

TOM: Or maybe he just wanted to impress his friend, who he knew would be too cool to ask what the hell he was doing? 

RAY: If that was his goal, it worked, John. Ask next time, will you?  


Dear Tom and Ray: 

We recently bought a used 1997 Toyota Avalon, which we love, but we are concerned about one minor problem. When you first start the car and for about the first five minutes of driving, the turn signal will not work at all. After that, it works perfectly. I can replace the flasher relay myself if that is all it needs, but I don't want to spend $45 on the part to find out that it isn't the problem. I also don't want to pay my dealer $50 to tell me it's my flasher relay. Since sticking my arm out the window won't sit well with my wife in January, could you tell me if you've run across this problem before? -- Ray 

TOM: Yes. And it's usually the flasher relay. 

RAY: I'd take the chance and buy one, Ray. It should solve the problem. By the way, that'll be $80. You did read the fine print at the bottom of our column, didn't you?