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1997 Honda Civic--mechanic says maybe the computer is bad

This is my girlfriend’s car so I’d better be right when I give her advice.

Two months ago the CEL light came on due to several intermittent misfire codes. The fix was a new distributor cap and rotor, new plugs and a minor tuneup.

The CEL just came on again. There are several codes, again all intermittent misfire.

The engine runs just as smooth as can be, as it did all through the last CEL episode.

Today, the mech says he needs to do some more checking but it’s looking like the computer is bad and a new one is around $700.

This is a well-meaning mechanic in a small-town shop.

How do I prove that the computer really is bad?

I can have the exact codes tomorrow if it helps address this problem.

I’m very relucant to put a $700 computer into this old a car without some very specific evidence that the computer is bad.

If it were my car I’d consider getting used to looking at the CEL light. However, this is a woman’s car and reliablity is more of a consideration.

Can it pass a California smog test with the light permanently on?


I doubt that the ECU is the trouble also. There are a number of sites that talk about the causes of misfires. Here is one of them. Checking for a clogged EGR valve would be a good first check I think.

You need to post the codes the computer is giving.

I’ve seen computers fail where they indicate many codes where the engine shouldn’t run, but it runs normally. And after digging far enough, you finally realize the computer is causing the problem. And if it is, you get a used unit from a local auto recycler.


I tend to agree, that ECU’s fail a lot less than people think. The issue is, they can only react to the information they are given; garbage in, garbage out. The specific codes might help a lot; it could be that a certain censor has failed, and the computer has gone into a ‘limp mode’, where the engine will nominally run, but not at peak performance.

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

If the mileage is less than 150k, call your Honda dealer. 1996 and 1997 Honda’s had a warranty extension for 14 yrs or 150k. Almost everything that can turn the check enigne light is covered.

Here?s the history:

119,000 miles, check engine light, I don?t have the codes, Shop ?A? replaced the spark plugs and ignition wires.

131,000 miles, now at Shop ?B?, codes p0301, p0302, p0303, p0304, p1300; replace rotor and distributor cap, replace spark plugs (again).

Today, 132,000 miles, Shop ?B? again: codes p0302, p0304, p1399

The last two times (no info on the first) the car was parked with everything fine. Upon starting the next day the light came on immediately. In both cases the engine started easily and normally and there is no roughness at all.

Today, Shop ?B? is looking at SB98-081 which calls out replacing the computer depending on certain freeze readings.

Yesterday they got RPM > 1100 and VSS 0 which are acceptable readings.

Today they got RPM 289 and VSS 0 which is not acceptable.

Unfortunately, I don?t really know what this SB is all about. I understand the concept of the computer and sensors and check engine light, but I don?t really know much about working with this in the real, everyday, world. I?m from a previous era of points and coils and carburetors.

I tend to doubt that the computer has suddenly gone bad. I did suggest to the mechanic that every connection to the computer and involved sensors be verified as nice and clean and shiny. He said he?d check this, but his face indicated he?d be happier popping in a new computer.

I?m interested to hear all suggestions.


In my state an inspector would not even begin the job if the CEL light were lit. I assume CA is just as strict.

I only had one computer fail on me. The car was a 1995 Dodge. The malfunction did not affect the CEL light, but it prevented the tach from working, and hence the cruise control as well. Also, the cooling fan ran constantly. After going nuts trying to correct these problems directly I suspected the computer was bad.

To find out for sure, I made a temporary swap of computers with a near-identical model. The problems were fixed, and I returned the computer. Searching the internet I found a guy who had parted out his Dodge and was willing to sell his computer for $10. Sold! I’ve had no problems since.

So that is my suggestion: find a cheap used computer from the same model Civic. They ought to be common enough. It’s either that, or go to a real mechanic who knows how to correct the actual problems. Whatever you do, make sure it’s done before your inspection sticker expires.

Good news-Bad News

Good News–I called a dealer with the VIN and, sure enough, this car is covered until its anniversary in-service date next March.

Bad News–I went to the shop to get the VIN number. The mechanic’s face was lit up. He had the coil in his hand and there was a burn mark where high voltage had arced. The adjacent bracket was burned and corroded as in maybe occasional arcing had been going on for some time. He had already ordered a coil and it is to be delivered this afternoon.

Bottom line–Assuming that the coil is the problem, I’m now paying for three service episodes that were likely covered under warranty. I wonder if the dealer would have somehow wiggled out of the coil, again, assuming that is the real problem. I do take notice that the first two episodes were merely throwing parts at the problem, a technique that does go back to my era. At least with the coil there is a defect you can see with your own eyes.

I’m hoping this will be the end of the story. Thanks TxDealer for pointing out the warranty info and thanks to everyone who contributed.

What I should have done is posted the problem on this board and then sat back for a day or two before taking the car anywhere.

Live and learn.


Thanks for the update on the trouble.

I have to wonder about how the hole was burned into the case of the coil. The coil could have been faulty but it sounds more to me that the coil output wire was bad and the coil voltage was seaking the nearest ground point.

It’s now the next morning and I’m waiting to hear from the shop. I’m guessing the coil was delivered too late yesterday to get it installed.

Here’s an interesting aside regarding the warranty extension concerning the check engine light.

I found and printed out the Honda service bulletin announcing the 14 year/150,000 mile coverage so I had some idea of what I was talking about.

I’m in a small town with only a Chevrolet dealer. The two closest Honda dealers are each a 45 minute drive away, one east and one west. I decided to phone each one and ask about the warranty coverage.

I first called the service department at the one that is an easier drive. The voice of the service person on the phone made it pretty clear that I was interrupting something, maybe his nap. He said that there was such a warranty, but it applied to only a very few cars, probably not mine. He made no effort to go any further so I thanked him and said good-bye.

The second service department listened to my question and then forwarded my call to a person they said could address the issue. The second person asked for the VIN number and quickly put it in the computer. In seconds he told me the exact date the warranty would expire and gave me a general description of the coverage. He gave me his direct line phone number and said to call back when I was ready to bring him the car.

I won’t belabor the obvious point. Both dealers, no doubt, spend a fortune on advertising and websites, but one dealer blew it by allowing an unhelpful person to answer a random phone call.

Eventually I’ll be buying a car. Since I want service after the sale I’m clearly not going to be going to the dealer that already demonstrated that their service department is hard to deal with.

Never mind eventually, I’ve already told the story—with names—to half-a-dozen people.

One dealer is wasting his advertising and web budget.