Well what is the code? or codes? If you have more than one O2 sensor they will each have codes associated with them if they fail.
To check the converter you could have the exhaust tested with an analyzer. The O2 sensor is easy to test as well. You just need to measure the voltage coming off of it and compare it to the specifications.
150K is well past what many of the manufacturers consider the "life" of a vehicle.
My CEL keeps coming on and my gas mileage is poor. The error code is "vague" and sounds like it could be the catcon or the O2 sensors. Isn't the catcon supposed to be good for life of the car? Would you replace the catcon or the two O2 sensors given my symptoms above? _______________________________________________
I would not replace either based on the sole symptom you cited (poor gas mileage). Please give more info:
Poor gas mileage will destroy a catalytic converter. It could be caused by the O2 sensor but you need the codes to determine that. Guessing at parts to replace is expensive and futile. The car needs to be diagnosed with an OBDII tester and then the correct parts can be determined. If you have been driving for a while with poor mileage the CAT is probably gone but the only symptom that will cause is pollution. It will have no effect on the drivability of the car
It's as cold as the exhaust pipe going into it? Can you borrow one of those infrared thermometers to take its temperature?
I've found that mechanics vary a lot in their diagnostic skills, and some don't seem to know how to interpret the OBDII codes, except literally. The O2 sensor before the cat should give out about 0.6V DC (measure only with a high impedance meter, like a digital voltage meter) or 1Vpeak-peak on a oscilloscope, while the O2 sensor after the cat should put out only a feeble signal if the cat is working, or a strong signal if the cat is bad.
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has factory manuals for 1996 and 2002 Proteges, as well as lots of other factory manuals for various makes of vehicles. A factory manual will cover the fuel/emissions systems in a lot more detail than any Chilton or Haynes manual will and in terms that are easier to understand. The next best reference is a Mitchell manual from a library, preferrably the paper version.
If I was tight on money, I wouldn't "have" them replaced but would replace them myself, but only after proper diagnosis proved that they were bad. The only thing I might "have" done by someone else would be a detailed diagnosis (i.e., specifies everything that has to be done and everything that has to be replaced) by a _good_ mechanic who knows all about Mazda fuel/emissions and doesn't make hit-or-miss guesses.
Have you tried the FAQs and forums at places like MazdaForum.com and MsProtege.com ?
But we have no idea what your symptoms are. You don't even tell us what the actual error code is, and you have made no measurements of any sort. What is the error code and what does the exhaust look and smell like?
can't a muffler shop put some sort of pressure tester prior to the catalytic convertor to see if there is excessive back pressure? That would make the most sense. If they can't, then here is an opportunity to make millions.
Who the hell knows? If you don't know why it went on, you don't know why it went out either. Without pulling the codes, you know nothing. Pull the codes.
You might want to check the Mass Air Flow Meter as well. I had those types of symptoms (vague computer lights, high petrol consumption) on my car (Skoda, VW engine). Had the car's computer read, the error codes pointed anywhere and everywhere. Tracked the fault down to the mass air flow meter. Swapped it out, it sorted it all.
If yours isn't actually knackered, but just dirty, have a butchers on the web for pages on how to attempt to clean your flow meter (usually a task involving some solvent to get the build up of crap off the two measuring wires (if that is the type of meter it has)), if there is physical damage, you'll have to shell out for a new one.
You might want to check the Mass Air Flow Meter as well. I had those types of symptoms (vague computer lights, high petrol consumption) on my car (Skoda, VW engine). Had the car's computer read, the error codes pointed anywhere and everywhere. Tracked the fault down to the mass air flow meter. Swapped it out, it sorted it all.
If yours isn't actually knackered, but just dirty, have a butchers on the web for pages on how to attempt to clean your flow meter (usually a task involving some solvent to get the build up of crap off the two measuring wires (if that is the type of meter it has)), if there is physical damage, you'll have to shell out for a new one.
This is a "catalyst efficiency" code, which the ECU sets when it sees the rear O2 sensor tracking too closely with the front O2 sensor.
This code will appear if either one of the O2 sensors is bad.. you would think that if the front sensor failed it would throw a bunch of other codes too, but not necessarily. It will also appear if the catalytic converter is bad or if the sensor wiring is bad or if the sensor inputs on the ECU are bad.
The next step is to use a real scanner and look at the values of the O2 sensor inputs that the ECU is seeing, both to see if they are out of range and to see what they do as the engine is warming up.
If you don't have access to a real scanner, all you can do is start swapping stuff out at random. Since you're losing power, I'd start with the front O2 sensor. If drivability is not affected, it's more likely to be the rear O2 sensor which exists mostly to make sure the catalytic converter is okay.
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