Excuse me for butting in here. What did your mechanic mean by "have it checked out"? The Engine Computer checks the operation of the catalytic converters while you're driving. What is anyone else supposed to check?
I didn't see anything here that points to a catalytic converter problem, at least with the replacement. The only thing that will damage a replacement is running leaded gas through it, and that wouldn't be the mechanic's fault, or driving with too much unburned gas entering the exhaust system, and the Check Engine light would have told you that. That's not the mechanic's fault either. I didn't read anything that is his fault so why are you itching for legal action? It sounds more like you need an engine performance specialist which most mechanics are not.
My main reason for sticking my nose in here after stumbling across this post is to clarify your misunderstanding about the Check Engine light. I read this real often and I think it stems from incorrect training that some mechanics receive or don't receive. Starting with all '96 models, there are well over 2,000 potential diagnostic fault codes that can be set relating to different things the Engine Computer monitors. Only about half of them refer to things that could adversely affect emissions and those are the codes that must turn on the Check Engine light. Any of the other 1,000 codes could be set in memory and never turn that light on. For that reason, the place to start with any engine running problem is by having the fault codes read and recorded. Whether or not the Check Engine light is or was on has nothing to do with it. Way too many car owners AND mechanics incorrectly think the Check Engine light has to be on to check codes.
You can also get an idea of the severity of a fault code by how the light acts. Once the six-second bulb check is done at engine start-up, the least serious problems never turn the light on, period. A very minor emissions-related problem will turn the light on while you're driving, and if it's an intermittent problem that stops acting up, the light will turn off, ... While you're driving. If it's more severe, the light will "latch" on and stay on, even if the problem stops acting up, until you turn the ignition switch off and restart the engine. Then the light will stay off until the problem is detected again. For still more severe problems, the light will be on anytime the engine is running, even if the problem stops acting up. The most serious problems are when the Check Engine light is flashing. That means bail out and head for cover! Well, actually, it means stop the engine as soon as possible because too much raw fuel is going into the exhaust system where it will burn inside the catalytic converter and damage it from overheating. You don't have to stop the engine instantly like when oil pressure is lost, but I wouldn't keep driving for more than 15 - 30 seconds if I could help it.
Also be aware, for future reference, there is always a long list of conditions that must be met for a diagnostic fault code to be set. One of those is certain other codes can't already be set. If a problem is detected for one circuit that is used as a reference for a second circuit, the computer knows it can't rely on the first one to make an accurate comparison, so anything that uses that first circuit with the problem will have some of its tests suspended. That means that while you're driving around with the first problem, (and a lot of people do with the Check Engine light turned and and glaring at them), a second, totally unrelated problem can develop, and you'll never know it since the light is already on, AND the test to detect that second problem is not being run. It isn't until your mechanic fixes the first problem that the tests resume and the second problem gets detected. That resumed test might run for the first time on his test drive or it might run when you're two miles from the shop, then the Check Engine light turns right back on again. Naturally you think the mechanic is incompetent, but in reality, all he had to base his diagnosis and repair estimate on was the one initial fault code. He had no clue there was another problem.
We hate having to tell you more tests, parts, or services are needed as much as you hate being told that, but we have no choice. This is an especially big problem on anti-lock brake systems on GM vehicles, but it happens on every car brand to some extent. This problem has a much greater chance of popping up anytime a computer-related warning light is ignored for a long period of time. That gives the new problem more time to develop.
As long as I'm at it, I must mention to be aware that diagnostic fault codes never ever say to replace a part or that one is bad. The people at many auto parts stores will read fault codes for you for free, but all they know is selling parts. A fault code only indicates the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a part is referenced in a fault code, it is actually the cause of that code about half of the time. When your mechanic diagnosis the cause of the code, you're paying him to determine what caused that code to set. That can include cut and grounded wires, stretched or corroded connector terminals, and mechanical problems related to a sensor, like air gap spacing and things like that. A sensor or other part is the last thing to suspect after everything else is ruled out. Too many people incorrectly think the computer's fault code tells you which part to replace. If it were that simple, you wouldn't need geniuses like HMAC300.
Tuesday, April 12th, 2016 AT 9:25 PM