2000 Legacy Alternator

This isn't your question, but I think that's too long to ignore a light.

If we had the actual code number, we might be able to advise specifically. Do you have any receipt with a code numebr on it? My instincts tell me that your alternator is fine - but....

Some auto parts stores (Autozone for example) will read the code, and sometimes clear a code (might need a $5 tip in some states...wink...wink)

There are many things that will turn the light on, from not tightening the gas cap well enough (a dozen or more 'clicks' may be required) to bad/lazy sensors (you may be due for a front oxygen sensor - they get 'lazy' intermittent in their old age) to TPS MAF failure or a simple misfire from old plugs or bad plug wires. If your are uncomfortable with the light on, either have the code read and post here, or find a good local mechanic. Personally, I might try a different one from the last place.

Carl

I do have the code on a receipt somewhere, but it is at home and I am at work, I will look for it when I get home.

A little bit more background on the situation, I had just been ignoring the light and it would come on, stay on for about three days and then go off, the car would continue to run fine. Then in September, the third time this happened, I took it to a local independent car fixer and he told me that it was the front oxygen censor and that there was a recall on this sensor and that I should take it to the dealer to have them replace it. He even printed information out for me about this recall. So I took my car to the dealer, the dealer told me it was the alternator and since they didn't know the history of the car, they were just going to clear the code and if the light came on again to come back.

So, now I don't know who to believe, they both gave me the same code. I have an appointment at a third car place in about a week and a half to have new tires put on, maybe I will just wait and have them look at it.

There is no code for a bad alternator. If it fails it may (but won't always) cause the "battery" warning light on the dash to come on. Sometimes they go bad in a way that does not turn the light on. A shop with the proper diagnostic equipment can fully evaluate your electrical system and determine the condition of the alternator and battery. Autozone will read codes for free, you should get them to do so and post the actual Pxxxx code here. Just stating that it's for an oxygen sensor is not sufficient to narrow the problem down, as there are quite a few different codes that are 02-sensor related. Even with the code however, there can be multiple causes. We can sit here on the Internet and speculate, but only a tech at a dealer or shop with their hands on the car can find the actual problem. So somebody along the line here is feeding you BS.

The Schucks here in Redmond, WA will read codes for free also.....Jim

So, I'm a big liar. I went back and looked at my paperwork and it is the CATALYTIC CONVERTER that the dealer told me the code was for. The code by the way is P0420.

So my original post should read:

Ok, that makes more sense now. If you have less than 80K miles on the car the catalytic converter is covered under the Federal emissions warranty which is 8/80, so your dealer should replace the converter for you for free. There may not be any symptoms as long as the converter is not clogged. When that code is set it indicates that the engine computer has determined that the catalyst is no longer performing effectively.

The only way the ECU can interpret the possibility of a bad cat conv is by comparing the upstream lambda sensor to the after-cat sensor. It is MOST likely you have a bad/lazy sensor. Have the front O2 sensor changed (OEM is prefered - try

) and the code cleared. If it returns, perhaps have the rear sensor changed. The price of those repairs will still likely be 1/5 the cost of a converter. Converters CAN go bad of course - but usually there are noticeable performance problems or other symptoms.

And don't use that first shop unless they can convince you the actually flow tested the converter.

Carl

While Carl MAY be right, generally if one of the 02 sensors is bad it will set additional codes that are specific to a bad sensor. This is true for the front sensor particularly, since it controls the engine air/fuel ratio and is carefully monitored by the ECU. Since you have already had a dealer confirm that the converter is bad you should ask for a free replacement under the 8/80 warranty as I mentioned, as long as your car does indeed have less than 80K.