Emission Control System light

Tiny
BLACKPUDDING34
  • MEMBER
  • 2004 MAZDA B3000
  • 3.0L
  • 6 CYL
  • 2WD
  • 97 MILES
The bloody idiot lights that Emission Control System light, it was on for years and years, it went off after I had fuel filter replace last month now

Its on again and will not go off, Truck runs very good, service recently I am told to ignore it but still worry, in the good days one did not need daft light to bug you non stop! If only they would make a simple vehicle with not dopey gadgets, I would love to buy one Cheers Jock PS is is good to chan ge Tranny fliud aftet 100 g and spark plugs also?

regards and thanks

Jock
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Sunday, January 12th, 2014 AT 2:56 PM

6 Replies

Tiny
WRENCHTECH
  • EXPERT
You quickly forget about all the benefits you get from technology.

That guy that told you to ignore the check engine light needs to go back to janitorial work.

The "check engine" light is an indicator for a system that monitors many electronic functions in the system, also called the "malfunction indicator lamp" (MIL). It can come on for any of hundreds of different causes from any of the systems that the computer monitors. Some are very important and can lead to further component or engine damage and some are emissions related not as serious but still a problem and need to be repaired.

Your first step is to have the computer scanned to retrieve the trouble codes that were set when the check engine light came on. Those codes will give you specific information about what the computer saw and will get you pointed in the right direction to find your problem. With a 1996 or newer and some 95 cars and you have an AutoZone or Advanced auto parts in your area, they will read them for free. Once you have these code numbers, we can be a lot more specific about what your problem may be
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Sunday, January 12th, 2014 AT 3:37 PM
Tiny
CARADIODOC
  • EXPERT
My sentiments exactly. I would buy a new car if it didn't have all of these ridiculous, unnecessary, unreliable computers hung onto every possible system, BUT, in the case of air bags, anti-lock brakes, and especially engine controls, there are real benefits and their cost is outweighed by those benefits. In this case you are to blame for your aggravation. Thanks to Chrysler's first use of electronic ignition in 1972 and computer controlled timing in 1976, engines run much cleaner and need fewer tune-ups. Thanks to electronic fuel injection, fuel mileage has gone up substantially. With those computer controls, there are more sensors and more things to go wrong. To make diagnosing a circuit with a defect easier and faster, the Engine Computer constantly runs self-tests on those systems, and it records a diagnostic fault code when it sees a problem. Those codes never say to replace a part or that they're defective, but they do lead you directly to the circuit or system that needs further diagnosis, or they indicate the unacceptable operating condition.

Things got more complicated in 1996 when they started monitoring the efficiency of the catalytic converters in the exhaust system. At the same time they began running self-tests for gas fumes evaporating from the fuel system. That adds another level of complexity by indicating problems related to two systems that have nothing to do with how the engine is running, BUT, it makes the exhaust so clean you can suck on the tail pipe and live to tell about it. That's a real big benefit.

Three things happened when you purposely ignored the Check Engine light. First of all, the majority of the problems detected have very minor causes that if left unrepaired, will turn into major problems. You did yourself a huge disservice by ignoring that warning. Second, even if you have the fault code read and choose to ignore it because it's relatively minor, if a second, totally unrelated, and serious problem develops, you'll never know it until it's too late because the warning light is already on. The problem could be a simple one resulting in too much raw fuel going out the exhaust system, wasted. That can overheat the catalytic converter and over time melt the catalyst and it will become plugged or ineffective. That's a very expensive repair.

Third, and most importantly, to set any fault code there is always a long list of conditions that must be met, and one of those conditions is that certain other codes can't already be set. The computer compares many things to each other to verify they're working properly. For example, it knows that after the engine has been off for at least six hours, the coolant temperature sensor and the intake air temperature sensor had better be reading the same temperature. If they are not, it has to figure out why or which one is wrong. If a problem is detected for the coolant temperature sensor, the computer knows it can't rely on those readings to compare to the intake air temperature sensor, so it suspends those self-tests. If a problem develops with the air temperature sensor, it is possible no fault code will be set, and your mechanic will not know about that second failure. It's not until the coolant temperature circuit is fixed that the self-tests on the air temperature sensor will resume. THAT'S when the problem is detected, the new fault code is set, and the Check Engine light turns on again. Usually the Check Engine light turns on with the new fault code right after the first problem is fixed, and you incorrectly think the mechanic didn't fix the problem properly. In reality, he had no way of knowing that second problem existed. That is your fault for ignoring the warning light for so long. The longer you ignore the warning light, the more time passes for additional problems to occur that no one will know about, ... Yet. A problem could also occur that has a serious affect on how the engine runs or fails to start, but if no fault code sets related to that new problem, there is no chance of knowing which circuit to even start looking in. You have to diagnose and fix the first problem first, (the one you chose to ignore), then HOPE the second problem will set a fault code, so you know where to start looking. Some fault codes related to no-start conditions only set when the engine stalls and the car is coasting to a stop. They may not set after the first problem is fixed and you're cranking the engine. Now you'll be paying for a lot more of your mechanic's time as he tries to figure out where to start looking. That added expense could have been avoided if you had just fixed that first problem years ago.

Also be aware there are well over a thousand potential fault codes the Engine Computer can store, and only about half of them make the Check Engine light turn on. Those are the ones that could adversely affect emissions. That means that by ignoring the light, you were getting worse fuel mileage all that time, and / or your car was polluting the air more than normal. I don't know who told you to ignore the warning light but that is the stupidest thing to tell a car owner. Replacing the fuel filter will definitely not cause the warning light to turn off. The fuel supply system isn't even monitored by the Engine Computer so it has no idea if a problem exists there. Even if it could set a fault code related to the fuel filter, for what possible reason would you not replace it? There are some fault codes that will self-erase if the problem goes away, but that isn't the type of code that was set if the light was on "for years and years". The same defect probably still exists that has always been there, and it's probably relatively minor, and your mechanic probably erased it with a scanner so the light would reset and turn off. Minor problems could easily take a month to show up again, and rather than find out what that simple cause is, you want to ignore it again and complain about it because you're lucky the engine is still running okay. At the very least, find out what the fault code is so I can suggest some possible causes and fixes, and give you some ideas on how to diagnose the cause. Your car has a defect and the Engine Computer knows what is wrong. NO ONE who understands cars would ignore that, especially for years.
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Sunday, January 12th, 2014 AT 4:04 PM
Tiny
CARADIODOC
  • EXPERT
Hi Wrenchtech. I wasn't trying to improve on or add to your dandy reply. I was just busy typing while you were posting.
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Sunday, January 12th, 2014 AT 4:08 PM
Tiny
MAXIMILIAM
  • ADMIN
Thank mate, I still hate the cars of today, no matter what annoying toys are forced upon us. My old VW beetle ran for decades, no tripe computer- bully ordering me about, and what savings? Rubbish. Shoved up the arse of the people, is what its called, pay for it and slave to it. Ok? I did Not ignore the daft light, it was the hideous emission light, the one that keeps the air so clean. Like LA and other polluted- to- the hilt- cities

Still Burning fossil fuels in 2014 ! But lots of chips and Big Brother add on's to slave to of course. As always the Japs/ Germans will lead the way out of the gas- burning loaded with
crap US vehicles Electric and a big breakthrough in charging, get rid of the petrol burning polluting heaps of today. Bring back the goddamn horse, a rifle a saddlebag, when men were men and sheep were nervous

Big Jock
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Sunday, January 12th, 2014 AT 11:59 PM
Tiny
MAXIMILIAM
  • ADMIN
Benefits from technology ! What about Choice? I do no want a car I must slave to.

Big Jock.
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Monday, January 13th, 2014 AT 8:46 AM
Tiny
CARADIODOC
  • EXPERT
I wasn't able to follow most of that rambling, but I agree that technology can be nice, but we're outpacing our need for it. "PowerPoint" is a tool for teaching that has its place, but for my teaching style, and the type of person I'm working with, it's not the right tool and is extremely ineffective. Try arguing that to department supervisors.

Who in their right mind wants to go back to horses, especially when you want to get to the hospital or your house is on fire, but you can't deny cars are a lot cleaner today than 20 years ago.

As for German engineering, you can keep that. It's not necessarily better; it's just different. It's the inappropriate use if technology that makes me roll my eyes. A computer for the heating system can incorporate some additional features, but nothing that can't be done with much more reliable cables and switches, and at a much lower repair cost. We used to use a switch on the transmission to allow the starter relay to operate. Now we use a switch on the transmission to turn on a computer circuit that electronically grounds that starter relay to allow it to operate. Remember the kids game "Mousetrap"? THAT is the inappropriate use of technology. How many times each month do I read about headlights not turning working on cars where they're controlled by a computer. What on earth do the headlights do that they didn't do before, and why do they need a computer to do it now?

My point in replying was not argue about technology. It was simply to point out that the Check Engine light is saying there's a problem, the computer has an idea of what that problem is, and there is no reason to not fix the cause. If you want to ignore something, ignore power door locks that don't lock by themselves. I'm sure most of us are capable of reaching a couple of inches to push a button. Ignore the interior lights that no longer fade out slowly, as long as they still turn on when they're supposed to. Don't ignore an emissions problem, especially when it makes it is so easy to prevent future engine problems. That IS an appropriate use of technology.
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Monday, January 13th, 2014 AT 7:53 PM

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