Does a check engine light have to be reset or will it go off on its own once the problem is fixed?

Question

The check engine light in my Mazda6 came on yesteday. The coolant level was low so I added coolant, but the light is still on? Does the light need to be reset or will it go off automatically? Or is there another problem?

Answer 1

The check eng. light means that the computer has detected a fault of some sort,so it should be checked for codes.As far as the light going out on its own,that would depend on the car make.On most cars,if the computer doesnt detect the fault again in 50 car starts (ign. on,ign. off)then it will turn the light off.

Answer 2

OMFG I have never seen such a bunch of MORONS in my life. WHY DO PEOPLE FEEL COMPELLED TO ANSWER QUESTIONS THEY KNOW NOTHING ABOUT??????

Change the oil- change the air filter- do a transmission flush- check CO2 sensor.... OMG, unbelievable wastes of money.

Anyway the coolant had absolutely nothing to do with your check engine light. It is completely coincidental, well not actually- your coolant was likely low for months but you didn't check it until the CEL came on.

There is absolutely no way to tell what emissions or engine control component is failing (and thus causing your CEL to come on) without getting it scanned. Even then, unless the person is a competent technician you at best get a identification of the general SYSTEM failure but not the specfic component failure. That's why so many idiots say things like "change the O2 sensor" because an illogical or out of range readout on the O2 sensor is usually not due to a bad O2 sensor but rather a fault elsewhere which is REPORTED by the O2 sensor.

So we know that you have an emissions or engine control failure and changing your $90 transmission fluid flush won't help (Octo, you idiot.). Unless we know what part is failed, we can do nothing and just guessing wastes time at best and money at worst.

Will the light go off by itself? Maybe. If whatever part failed to cause the code was just temporarily glitched, the light will go off after "n" number of drive cycles that the fault does not recur ("n" varies for the type of malfunction). Even if the light goes out it is still retained in memory for another 80 drive cycles or so and if the fault happens again the light will immediately return. This of course will also be the case if you reset the light without fixing what caused it.

As long as the light isn't flashing (blinking) you will not do dfamage driving with it on, but if you have emissions tests in your area you will immediately fail the test if the light is on (even if you reset it immediately before taking the test).

Get the free scan at autozone but DO NOT be talked into buying parts especially an expensive one because the person behind the counter might be one of the idiots who previously answered.

Thanks in advance for your best answer vote and I now return you to a swarming flock of morons.

Answer 3

The light needs to be reset...but before you take it to a dealer, check around for local mechanics and see what is involved. With newer Chevrolet vehicles, for instance, when the "change oil" light comes on, even if you've had it changed, the light has to be reset. I originally took it to a dealer and was charged $25 to reset it...even though, what I found out later made me really mad. To reset this light, all you have to do is place the key in the ignition, and turn it to the on position, but don't start the engine. All the lights will come on. By depressing the gas pedal 3 times, the "oil" light will start to blink. Turn the key off, take it out, then put it back in and start your engine like you would normally. The light will then turn off. You have to remember, that the dealers aren't going to hook up a car each time a light needs to be reset, so there is probably an easy fix for that light as well. It's just that the dealerships want to continue to make money and won't be upfront and tell you.

Answer 4

There could be another problem. You may need to change your oil or your transmission fluid, or change your air filter.
Sometimes they do need to be reset. The way to reset them is to disconnect the red battery cable for at least one minute, and then reconnect it.
Sometimes the check engine light can not mean anything though. Sometimes a bad sensor can cause the light to come on.
I would try changing the oil and air filter first. Those things don't cost that much money.
Changing the transmission fluid is kind of costly, about $90, so do that last.

Answer 5

to reset
.turn on the key without starting and push the odometer reset bottom and hold for a moment.
That will do it.
if not,
disconnect the negative of the battery for more than ten seconds
the third choice.
take it to the mechanic,to "hook up" the OBD scanner and push the erase codes bottom on the scanner.

PS and the last idea,get a big hammer and BANG hamering the frieking lite out.

Answer 6

it could be your sensor, or the best thing to do is go to a mechanic, and they can hook up a diagnostic machine to your engine and tell you which codes pop up and what they mean. My check engine light stays on since the 1st week I bought my car ( a neon) They reset it but it popped right back on later that night. Not much is wrong except a CO2 code pops up. no biggie. best thing would be take it in!! good luck

Answer 7

I'd have to agrre with "unclebernie"
Give him 10 points.

Answer 8

most parts stores will scan and reset lites for free..[Advance]