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Check Engine Light: What Does It Mean and Can You Turn It Off? | Allstate Insurance - YouTube
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Hey everybody, it’s Charles from HumbleMechanic.com
and today we’re talking about the dreaded
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“check engine” light.
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When the check engine light comes on in our
car, it can be a pretty scary thing. Then
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little amber light will pop on in our dash
to let us know something’s wrong, but it
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doesn't really tell us much more than that.
So today I'm gonna break down what the check
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engine light means, what to do when it comes
on and how we can make it go away.
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The check engine light in our cars is there
as part of a warning system that lets us know
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that, hey, there's an issue with the powertrain
of our vehicles. The powertrain can be our
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engine; it can be our transmission; if we
have all-wheel-drive it can include the all-wheel-drive
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component. Basically, all the things that
we need to make our car actually move are
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considered part of the power train. So, when
that check engine light comes on, those are
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the systems that were initially focused on.
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Now there's a ton of reasons that our check
engine light can come on. It can be a simple
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problem, like maybe the last time I put fuel
in my car, I didn't tighten the gas cap all
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the way. It can also be a really, really in-depth
problem with sensors or wiring or really anything
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in between. Every time we drive our vehicle,
even sometimes when the key is simply turned
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on, our car is running a series of tests.
These tests are run to make sure that things
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in our car are functioning properly, not only
for emissions controls, but for drivability
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issues as well.
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Now, when the car's engine computer sees a
problem--sees a failure of one of these tests--it
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turns the light on to let us know that we’ve
got something going on and we need to get
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it taken care of. There's basically two types
of monitoring that our engine computer does:
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there's continuous monitoring and non-continuous
monitoring.
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Alright, let's look at continuous monitoring
first systems in our vehicles engine that
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are continuously monitored are basically being
checked anytime the engine is running. Some
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really common ones are engine timing concerns
and misfire concerns. Those are monitored
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any time the engine is running and that's
mostly because if something goes wrong with
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that, there can be catastrophic failure pretty
quickly.
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Now, when it comes to non-continuous monitoring,
our ECM or engine computer, sometimes also
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called the PCM for powertrain control module,
will run these tests when the conditions are
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right. For example, when your engine computer
runs the catalytic converter test it has to
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run that test when the catalytic converter
is at the proper temperature. If it tried
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to run that test when the catalytic converter
wasn't, it would fail. These are really how
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most things are monitored in your car. These
can also be called two-trip monitors because
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generally it takes to failures before the
check engine light will actually come on in
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your car.
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Alright, so let's break down exactly what
this check engine light can mean. If your
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check engine light comes on, it's not a big
surprise that your car is telling you: Hey,
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I got something wrong, you need to take me
and get me fixed. But it doesn't really tell
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you much more than that. You're going to need
some kind of diagnostic tool to access your
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engine’s computer. If your car's ‘96 or
newer, you're on the OBD-II
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platform, which means that the automotive
industry has set standards for certain things
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like where your data link connector is and
what information has to be given when a check
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engine light is stored. What that means is,
you don't have to take it to a specific dealer
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for the brand to get it inspected. You can
take it anywhere that has these OBD-II diagnostic
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capabilities and have the check engine light
checked.
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When we hook this diagnostic tool up to your
car and go into the engine computer, it can
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give us information like fault codes. Fault
codes give us the system that has a failure,
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but it may not tell us exactly what the problem
is. For example, a fault code might look something
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like this: P0300. The first character will
point to the area of the car. The P stands
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for Powertrain. Faults can also begin with
B for body, a C for chassis or U for undefined.
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A lot of times when you see a U code, that's
a manufacturer-specific code and that's one
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of the cases where only the dealership might
be able to have that information. The second
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digit will tell you the code is generic, meaning
the same on all ODB cars, or manufacturer-specific.
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Zero indicates a generic code and a 1 would
indicate a manufacturer-specific code.
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So, in our P0300 code we know that we had
a powertrain code and then the next digit
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is a zero so we know that this is a generic
code that would apply basically to all cars
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that are OBD-II.
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Now, the third character is where it starts
to get interesting, because this gives us
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the subsystem of the fault. 1 is engine management;
think air and fuel system. 2 is the injector
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circuit it can also be the fuel or air system.
3, like our example, is engine misfires. 4
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is emissions controls. The catalytic converter
example I just mentioned, that code typically
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would be a P0420, indicating that there's
a problem with the catalytic converter. 5,
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we have vehicle speed and idle control. 6,
computer and output circuits. 7 and 8 are
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both transmission, and then 9 and 0 are reserved
for the SAE. SAE is the Society of Automotive
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Engineering. Now, these are the folks that
put together basically all of these standards
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for the automotive industry.
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Now, I've given you guys a few different examples
of engine fault. That P0300 fault, we know
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that’s a powertrain fault that is generic
across the OBD-II spectrum; 3 is an ignition
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problem. Now the last two digits are going
to be the identifiers. So, if this were a
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four-cylinder car and we had a P0300 and a
P0301 appears, we would have a cylinder one
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misfire. If it was a P0302, it would be cylinder
two, and so on.
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So what do we do with our check engine light
comes on? Well, there's three basic states
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to the check engine light. There's the check
engine light is off. That means everyone is
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happy and that is ideally what we want to
have going on. We have our check engine light
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where it is simply illuminated. That means
our car has a problem and we do need to get
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it checked as soon as we possibly can. We
also have on and off flashing. This points
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to an engine misfire. This can be a very serious
thing. We want to make sure that we're not
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driving a vehicle with flashing check engine
light -- it can do damage to our catalytic
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converter. Getting your car towed is highly
recommended if it has a flashing check engine
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light.
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Alright so what are we doing this check engine
light comes on? Well, we have several options.
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We can take it to our local dealership and
have them do a full diagnosis. Dealerships
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know cars very well; they know their brands
very well; so, that's a great option. There's
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also a ton of really great independent shops
that specialize in maybe the brand of your
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car, and you can even take it there for a
full diagnosis. There's also a third option
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and that's purchasing our own OBD-II scanner.
Now maybe something like this OBD-II scanner
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and you can even use something like your cell
phone -- pair the two -- and we can look at
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what's going on with our own car.
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With each of these options come some pros
and some cons. If we take our car somewhere
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-- to the dealership or to an independent
shop – odds are we're going to charged the
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diagnostic fee. But the good thing is, they
should have all the information and all the
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equipment to properly diagnose what's going
on with your car's check engine light. Using
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our own OBD-II scanner like this one may save
money on the diagnostic process, but we might
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not have all the repair and all the diagnostic
information. We may also lack the test equipment
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to properly pinpoint exactly what's going
on with our car.
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Before you decide to DIY or not to DIY, I
highly recommend you check out another video
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that I did called seven simple car DIY mistakes.
That will give you more information to help
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me decide do you want to do a DIY, or is this
something better left to the professionals.
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Now we understand a little bit more about
what this check engine light means, let's
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talk about how to get rid of this pesky little
light. The best course of action, of course,
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is to get your car fixed -- whether that's
a DIY or whether you take it to a professional.
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The best thing obviously to do is to get whatever
problem your car has completely taken care
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of.
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Again, this could be as simple as maybe tightening
the gas cap all the way. It can also be as
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complex as maybe needing an entire fuel system
in our car. But after these repairs, were
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also going to need to clear the check engine
light and let the car run all of its tests
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again to make sure that we don't have any
secondary issues going on.
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For the most part, even the DIY OBD connectors
can clear the check engine light once we get
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those codes cleared, the car’s going to
need to re-run all those tests. In order for
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all of those tests to run, the car has to
complete what's called a drive cycle. This
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varies tremendously from manufacturer to manufacturer
and it basically puts your car in several
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different driving situations – be it cold;
be it hot; maybe cruising on the highway;
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acceleration and deceleration…in order to
run all the test to test all the components
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your ECM or your engine computer does monitor.
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All of these tests that run, whether it's
on a drive cycle, whether it's forced with
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a diagnostic tool, is called setting readiness.
The readiness monitor is seen by the engine
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computer as an eight-digit set of zeros and
ones, and this can tell a technician what
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test run and passed and what tests haven’t
passed yet.
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In several states that have emissions inspections,
when your car set up to the states computer
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that's what they're looking for. They're looking
for all those readiness monitors to be set;
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all those tests to be passed. Now, it's not
generally recommended to just go in and clear
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the faults out. As a professional technician,
I will do this from time to time but it's
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not just to erase the code so the light’s
not on, it’s generally part of the diagnostic
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process.
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See, when you delete these faults it also
deletes very important engine information.
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Some faults will be stored with parameters
to them: Was the engine hot? Was the engine
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cold? What RPM was the fault stored? And these
things can be vital for a technician in order
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to properly diagnose what's going on with
the car. When you delete the fault, it also
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erases that information and that can make
check engine light diagnosis even more difficult
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than it already can be. So if you have a problem
with your car, I generally don't recommend
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just simply clear the fault.
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Alright guys I'm going to go ahead and wrap
it up there. If you have any questions comments
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or check engine light stories, feel free to
post it down in the comment section below.
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If you want to check out more of my videos,
head over to HumbleMechanic.com, you can see
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them all. You can also follow me on Facebook,
Twitter, Instagram and YouTube. Remember guys,
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when your check engine light comes on, don't
necessarily panic, but I also really don't
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recommend waiting too long to get it fixed,
because that can actually cause more problems.
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Alright guys, thanks for watching and I will
see you next time.
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