I went to auto zone and they hooked my car up to their little machine to figure out why my check engine light is on. This is what I found out.My catalytic converter is defective because I might have these problems:Engine misfire or running condition.Large vaccuum leak.Engine oil leakage into exhaust valve guide seals, piston rings.Can anyone give me a simple explanation of what that means? I have a 1998 Ford Escort wagon. Anyone know how much that will cost to fix?
The Cat simply burns off excess fuel (Hydrocarbons) in the exhaust and cleans it up to reduce emissions. The possible causes are not limited to the list you give. First you have to realize that your cat may well be working properly. The computer uses O2 sensors before and after the cat to determine how well it is working. Its possible that the downstream (after the cat) sensor is starting to fail, and sometimes it will read too closely to the upstream (before the cat) sensor. This makes the computer thing that the cat is faulty when it is not. This is just 1 possibility out of many, a prime reason that people must realize that a computer can NOT just tell you whats wrong with a vehicle. Most problems require a technician that has the knowledge and understanding of these systems who can actually test to verify the problem before they begin replacing parts. ***ADDED*** Now that i read your added details, I can explain a touch more. The EVAP system does not deal with the cat, if Auto Zone told you it does, then they are wrong. The EVAP system is concerned with reducing HC emissions in the fuel before it is burned off. This includes the gas tank and charcoal canister, and the lines and actuators in the EVAP system. The vehicle will pressurize the entire system with a very low pressure and it has to hold the pressure for so long or it determines there is a leak and usually sets a check engine light. If this is the case, start by removing your gas cap and re-tightening it. Beyond that, you'll have to have a shop smoke the system. This is where they fill and pressurize it will a non-harmful smoke and look for the leak. Good luck.
A defective catalytic converter is one that doesn't properly reduce emissions. Right now I'm looking at one of the sites I go to for parts and I could have the part for $115 It's been said you may have a misfire though you'd probably notice that so I'd rule that out, a large vacuum leak would cause a misfire so I wouldn't blame that and if you notice a problem with oil running low you can blame that for the cat failing.
There is no indication of a defective cat. You could have a misfire but the codes aren't provided so it's hard to say. a large vacuum leak would seriously affect your engine. It would be running rough and stalling at idle. There is no way an oil leak can be detected with the little machine. Whoever told you this is preparing to rip you off with repairs that are not needed. I would try elsewhere to get the codes read. Post the codes here and maybe get some help.
