Check Engine Light
 

Hello,
I have a 1997 Protege with over 180,000 miles on it. It has been a great car! However, there is a recurring problem that I've had with the check engine light (CEL) since about 60K or 70K miles, and I wanted to see if anyone had experience with this.

The light first came on and went off from time to time, until it stayed on permanently. I took it to Mazda and they diagnosed it and said that I needed new O2 sensors and a catalytic convertor. The price was outrageous, so I had a friend replace the O2 sensors and left the catalytic convertor as it was. The CEL went off for several months and then came back on again. I left it for the remainder of the year because the car was driving great.

When I went in for my inspection in December, it wouldn't pass because the CEL was referring to an emissions problem. I took it to Midas (knowing the Mazda dealer would be really expensive) and they suggested replacing the 1st stage catalytic converter, as Mazda had suggested before. This was a $600 job, but I had it done, and the CEL stayed off for another 2-3 months. Now it is back on again and my inspection is coming up in December. If I take it to Mazda and they tell me that I need my O2 sensors and catalytic converter replaced again, it will be upsetting news as you can imagine!

I talked to my neighbor who has the exact same car, except with quite fewer miles, and she has had the exact same problem as me. Mazda suggested the same repair to her.

Has anyone else experienced this problem, or does anyone know what the root cause might be?

Thanks,
Dave

Hey, Dave. If you want to save some money, stop by the Autozone. They will give you a free diangnostic of CEL, and you can go from there. I could only suggest to check your O2 sensors, as you have two of them. Perhaps this time its a different one that went out of order, and also check to see if your exhaust header might be cracked.

My '97 LX has about 65K miles on it and I have a similar problem. The CEL first came on about a year ago when I brought my car for a check-up at the Mazda dealership. They performed a X mile (can't remember the miles) service and about 3 days later the CEL came on. I am getting some rough idle and poor gas-mileage. I had the problem diagnosed and it turns out that my 4th cylinder is misfiring. Further tests showed that the compression on that cylinder is lower than the others. I changed spark plugs, distributor cap + rotor, but the problem remained. The final offer I got was around $900 for a resurfacing of the cylinder heads or head gasket or something like that. I don't remember exactly, but something had to be machined. I thought that $900 was too much, and decided to do nothing. I've been driving the car like that for about 6-7 months and nothing has changed. I am too afraid to go and have the car checked again because I've been to three different places, and all of them did the same - told me that I have a 4th cyl. misfire and I should take the car to Mazda because only they would know how to fix it (and each of those charged me a good amount of money for diagnosing what I already knew). The OBD code is just that - 4th cyl misfire. Could that be related to a bad O2 sensor or a faulty catalytic converter?

Check Engine Light
 

I think that would be a different problem. The catalytic converter and O2 sensor problem has caused no noticeable performance problems for me. The car idles well (although I did have a problem at the beginning with it choking off, but a dealer found that an air hose or something similar was loose, tightened it, and it has been in great condition since), and the gas mileage is great (38-40mpg - I do mostly highway driving). I think that the 4th cylinder misfire diagnosis may be correct if several people have said the same thing. If it is affecting the car's performance and gas mileage it might be a good idea to go ahead and have the work done at Mazda. I would also try to find out if this problem could cause engine wear and shorten engine life. In that case I would definitely get it fixed.
Dave

Intruder. Your cylinder compression loss is a serious issue, and your are really pushing your luck. You are only making your problem much worse then it is already. Your problem is probably a blown piston ring. Which probably lets some of the oil to be burned during combustion. It also damages your cylinder walls, therefore, it is very importand to detect this problem right of the way, or it will cost you a lot more in the long run.

The only thing that's been keeping me from doing this at the dealership is the steep price. Those guys are killers! I guess there is no alternative because all the three other place I went to couldn't do a thing. I'll have it checked as soon as possible - I don't want to kill my Protege yet.

My CEL came on at 69k and goes on and off. I was on the whole month of october, but went off the day i did emissions testing. Came back on the day after and is still on. Hooked it up to a code scanner and no codes came up. Right before it happened the cylinder on the far passangers side, either 1 or 4, the sparkplug had completely unscrewed it's self and the engine was still firing with it unscrewed. No loss of power, no loss of mileage, and no idea how to fix it.

Do you have rough idle?

My idle is perfect

I see

my CEL has been on for a couple months on and off, if i reset it, it will go off for about a day then come back on. I think i also may have a cracked manifold or cracked exhaust pipe as when i turn on the car in the morning and turn on the heat i can smell exhaust.