Unveiling the Mystery: Codes Without Check Engine Light!
Yes, you can get a code without the check engine light on. A check engine light is a warning light that indicates a problem with the engine. However, there are many other codes that can be stored in the vehicle’s computer that do not trigger the check engine light. These codes can indicate problems with emissions, transmission, or other systems.
So Can You Get A Code Without Check Engine Light On
A check engine light is a warning sign that something is wrong with your vehicle. But what if your check engine light isn’t on, but you still have a code
There are a few reasons why you might have a code without a check engine light.
The code is stored in the computer but hasn’t been triggered yet:
This can happen if the problem that caused the code to be stored isn’t severe enough to trigger the check engine light.
The code is stored in the computer but has been cleared:
This can happen if you take your car to a mechanic and they clear the codes.
The check engine light is burned out:
This is a rare occurrence, but it can happen.
If you have a code without a check engine light, it’s important to have it diagnosed by a qualified technician. The code could indicate a serious problem that could lead to damage to your vehicle if it’s not fixed.
Can You Get a Code Without Check Engine Light On?
Yes
You Can Get Diagnostic Trouble Codes Without the Check Engine Light Illuminated
As an automotive manufacturer and dealership
we understand the importance of diagnosing vehicle issues accurately. One common misconception is that diagnostic trouble codes (DTCs) can only be retrieved when the check engine light is on. However
this is not entirely accurate. In modern vehicles
it is possible to have stored trouble codes even if the check engine light is not currently illuminated.
Reasons for Stored Diagnostic Trouble Codes
There are several reasons why a vehicle may have stored diagnostic trouble codes without the check engine light being on:
- Intermittent Issues: Some vehicle problems may occur intermittently
causing the check engine light to turn on and off. However
the diagnostic trouble codes related to these issues can still be stored in the vehicle’s computer system. - Non-Emission Related Codes: Certain vehicle systems
such as the transmission
ABS
or airbag systems
can generate diagnostic trouble codes that are not directly related to emissions. These codes may not trigger the check engine light but can still be accessed using diagnostic tools. - Pending Codes: In some cases
the vehicle’s onboard computer may detect a potential issue and store it as a pending trouble code. If the issue does not persist over a certain number of drive cycles
the pending code may not cause the check engine light to illuminate
but it can still be retrieved through diagnostic scanning.
Retrieving Diagnostic Trouble Codes
For both manufacturers and dealerships
it is essential to have the capability to retrieve diagnostic trouble codes
regardless of whether the check engine light is on. This is typically done using an OBD-II (On-Board Diagnostics) scanner
which can communicate with the vehicle’s onboard computer to retrieve stored codes. These codes provide valuable insight into the health and performance of various vehicle systems.
Importance of Addressing Stored Diagnostic Trouble Codes
Even if the check engine light is not currently illuminated
addressing stored diagnostic trouble codes is crucial for several reasons:
Can a Car Throw Codes Without a Check Engine Light?
The invention of self-diagnostics for cars was one of the most significant breakthroughs in the automotive industry. With its inclusion, car owners didn’t have to learn the details of their vehicle or guess when something breaks down, as the vehicle’s computer would handle the diagnostics for them.
In the early days, there was only the check engine light which covered almost all the faults, save for battery, brakes, and a few others. Modern vehicles have more than a dozen dashboard lights which raises the question of when and what code is triggered.
Your car can throw codes without the check engine light if the problem is intermittent, although usually, it means it’ll turn on and off depending on when the fault is triggered. The code may also come with a different warning indicator, like the ABS or brake light for example.
Why Some Fault Codes Don’t Trigger the Check Engine Light
As we mentioned earlier, the ECU constantly monitors everything the engine is doing in real-time thanks to all the sensors. That includes ignition, air intake, exhaust, camshaft, crankshaft position, and the charging system.
Now, it happens every so often that, for example, the engine randomly misfires. In such cases, the ECU won’t trigger the check engine light because an occasional misfire is considered normal.
The same goes for the knock sensor, high coolant temperature readings, and all other parameters. And if the ECU was programmed to trigger the check engine light every time it sees an abnormal sensor reading, it would light up at least every couple thousand miles in older cars.
Instead, the ECU is programmed to monitor and save long-term data. Then, if it notices a certain sensor reporting abnormal values too often or for a long period, it will trigger the check engine light.
However, the fault code will be stored even after the first time it happens. So, if you notice any odd symptoms in how the engine runs, the first thing you should do is scan the fault codes even if you don’t see a check engine light.
When Does the Check Engine Light Come On
As already mentioned, the check engine light comes on after a certain sensor reports abnormal values too often in a specific time window. However, if a certain faulty component has the potential to cause damage to the engine, the check engine light will come on immediately.
For example, if the ECU notices the camshaft timing isn’t correct with the help of the camshaft and crankshaft position sensor. Furthermore, you could see the check engine light come on and turn off after a while. In such cases, a certain sensor could send values outside the normal range. For example, a coolant temperature sensor reports values between 0.5 and 1.5 volts, and then it sends a value of 2 volts.
Now, when the ECU sees an out-of-range value coming from the temperature sensor, it shuts the sensor down and lights up the check engine light. Then, when you restart the engine, the sensor continues sending values in the correct range, and the ECU has no reason to trigger the check engine light.
However, the sensor is still faulty, and the first time the check engine light came on, a fault code was already stored, and you will find it with an OBD scanner.
Also, the check engine light could also be flashing under certain conditions, and that indicates a more serious and urgent problem. For example, that happens when one of the ignition coils fails. And just like it’s the case with the temperature sensor, the ignition coil will typically go back to normal after a while, and the check engine light will turn off. But again, a fault code is stored.
Can Faults Exist Without a Check Engine Light or a Fault Code
Now we get to the real problem of the OBD system. Previously I mentioned the voltage values and ranges that the sensors use to communicate with the ECU. Well, we will stick with the coolant temperature sensor to explain this as well. So, let’s say 0.5 volts coming from the temperature sensor tells the ECU the coolant is at 30C (cold). And at 1.5 volts, it tells the ECU the coolant is at 150C (overheating).
Now, when the temperature sensor is faulty (and thus goes for all other sensors), it will naturally send false information to the ECU. For example, it sends 1.5 volts telling the ECU the engine is overheating when in fact, it’s cold.
In turn, the ECU cuts back on the ignition timing and enriches the air/fuel mixture. That results in a car that’s low on power, has increased fuel consumption, hesitates, runs rough, etc.
However, as long as the temperature sensor is sending values that fall in the correct voltage range (0.5 to 1.5), the ECU will trust the sensor and won’t store a fault code or trigger the check engine light.
And the only way you cm diagnose such an issue using the OBD port is to get a program that allows you to monitor live data. That way, you can see in real-time what a certain sensor is communicating to the ECU.
How to Read Fault Codes
Before we cover the different OBD2 readers, it’s worth mentioning that certain cars have an integrated fault code scanner, for example, in the early 2000’s European GM vehicles (Opel).
In that particular case, you would press the gas and brake pedal simultaneously and hold them while you turn the ignition on. After that, you would write down the check engine light flashing sequence, and you would get the fault code.
Of course, the method of getting this readout differs between manufacturers, and again, not all cars have it. Furthermore, you can use this system to only read the fault codes, and in the end, you will need an OBD2 reader to delete them.
OBD2 Fault Code Reader
An OBD2 adapter which you can see above uses a conventional cable and an interface unit. This is probably the easiest way to read codes and delete them. Also, if you buy a more expensive one, you will likely be able to read live data as well.
Anyway, this is the best option if you plan on using it on two or more different vehicles, and you don’t need any special computer or smartphone software. Also, the user interface is easy to use, making it a great beginner option.
Prices pulled from the Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
OBD2 Bluetooth Adapter
The OBD2 Bluetooth adapter is probably the most popular option in recent years, mainly because they are significantly cheaper than the equivalent readers. However, note that you will need to install a corresponding software/app on your smartphone to use it.
Unfortunately, all the quality apps require a one-time purchase or a monthly subscription, but a good number of them offer lite versions for free. Luckily, the lite versions let you read and delete codes, as well as monitor live data, and that’s more than the average driver is ever going to need.
Prices pulled from the Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Veepeak OBDCheck BLE Bluetooth OBD II Scanner Auto Diagnostic Scan Tool for iOS & Android, Bluetooth 4.0 Car Check Engine Light Code
Is It Okay to Drive With a Check Engine Light On?
Yes, it’s okay to drive with a solid check engine light. However, if you notice the check engine light flashing, that’s a sign of a more serious issue, and you should avoid driving. The same goes if you see any other warning light that’s red instead of yellow.
Is Check Engine Light Serious?
No, a check engine light isn’t serious in the sense it will cause immediate damage to the vehicle or that it will soon stop working. However, issues that trigger a check engine light can be expensive and difficult to fix, so, in terms of money, it can be serious.
Can a Check Engine Light Turn Off by Itself?
Yes, a check engine light can turn off by itself. For example, if a certain part or sensor is failing intermittently, the check engine light will come on when the part stops working properly and turn off when it comes back online. Also, as soon as you replace or fix the problem that triggered the check engine light, it will turn off on its own.
Can Low Oil Cause a Check Engine Light?
No, a check engine light isn’t related to low oil. Those cars that have an oil level sensor also have a designated warning light for low oil unrelated to the check engine light. That warning light is yellow, and it’s a symbol of an oiler can. Also, low oil pressure will have the same symbol, but it’s red instead of yellow.
Are Fault Codes the Same for All Cars?
Yes, fault codes are the same for all cars. And even though some brands have their own fault codes, they will still throw the generic fault codes too. Those are all fault codes that start with P0000 (powertrain), C0000 (chassis), B0000 (body), and U0000 (user network).
Can a Car Throw a False Code?
No, a car will never throw false codes unless the ECU (engine control unit) is broken. But keep in mind that the ECU fault codes should never be taken as is. Instead, one fault code can mean one thing, while the same fault code in combination with another one can point to a third unrelated component. That’s why reading fault codes when your car has a more complicated issue is best left to professionals.
Will a Car Fault Code Clear Itself?
No, a car fault code won’t clear itself. Even after you replace the faulty part or fix whatever triggered the code, it will still be saved in the ECU memory until you delete it manually. But again, a check engine light will turn off after you fix whatever caused it.
Does Removing the Battery Clear Fault Codes?
No, removing the battery won’t clear fault codes. However, removing the battery and then connecting the two battery terminals together will drain the ECU capacitor and clear the ECUs memory. But keep in mind that this method only works on older cars.
Conclusion
So, now we have become a little more familiar with fault codes, warning lights, and how sensors communicate with the ECU; hopefully, it’s easier to understand why a car can have stored fault codes without a check engine light. That makes it easier to diagnose any potential issues in the future, and rest assured that you will see a check engine light if the problem which caused it becomes more serious.
And lastly, it’s also worth mentioning that sensors and other parts can be faulty and not trigger any fault codes or a check engine light. That’s why monitoring live data is important if you notice any odd symptoms without any clues in the OBD2 system.
Here are some articles that you might enjoy:
Can A Car Throw Codes Without Check Engine Light?
Did you know that your car can also throw codes without the check engine light? It is important to understand how your car can communicate with you as a car owner.
Yes, a car can throw codes without the check engine light. The check engine light is not always directly connected to the code-throwing mechanism. Sometimes, there may be a loose connection or a wiring issue that prevents the check engine light from coming on even when thrown codes.
This blog will highlight why cars can throw codes without the check engine light. It is important to know why this happens so that you can take the necessary steps to fix the problem. Have a close look with us!
Table of Contents
Why Can A Car Throw Codes Without Check Engine Light?
It’s not uncommon for a car to throw codes without the check engine light. There are a few reasons why this could happen.
One reason is that the engine computer controls the check engine light, and if there’s a problem with the computer, it may not be able to turn on the light. There are two different types of codes that your car’s computer can generate fault codes and information codes.
- Engine fault codes are the ones that will turn on the check engine light, and they indicate a problem with your car that needs to be fixed.
- On the other hand, information codes don’t necessarily indicate a problem. They’re just meant to provide information about what your car is doing.
Another reason is that the light may be burned out. It is important to have the codes read so you can diagnose and fix the problem. You can usually do this at a local auto parts store or repair shop.
Does The Check Engine Light Have To Be On To Pull Codes?
Most people think that the check engine light (CEL) has to be to pull codes from the vehicle’s computer. However, this is not always the case. The CEL may not be illuminated in some instances, but it can still pull the codes.
It’s also important to note that not all codes will trigger the CEL. Some codes may never trigger the light at all. These are typically less serious codes that don’t necessarily indicate a problem with the vehicle.
Can AutoZone Read Codes Without Check Engine Light?
The answer is yes; AutoZone can read codes without the check engine light illuminating. While the check engine light is not required for AutoZone to read codes, it can help identify the problem. If the check engine light is on, it’s good to have the codes read as soon as possible to diagnose and repair the issue before it causes any further damage.
Does Autozone Charge For Diagnostic Tests?
If you’re wondering whether or not Autozone charges for diagnostic tests, the answer is no – they do not.
There are several reasons why this is the case, but the most important is that Autozone wants to provide its customers with the best possible service. Offering free diagnostic tests can show their commitment to customer satisfaction.
In addition, Autozone knows that many people are not able or willing to pay for a diagnostic test. They want to ensure that everyone has access to the same high-quality service, regardless of their ability to pay. Ultimately, this is just one of the many ways that Autozone shows its dedication to its customers.
Is Autozone Accurate?
According to customer reviews, Autozone is generally accurate when diagnosing car problems. Of course, no one is perfect, and there will always be some cases where they’re not 100% spot-on. But overall, they do a pretty good job.
So if you’re having car trouble and don’t want to spend a lot of money on a diagnostic test, Autozone is worth checking out. If you’re still unsure about what’s wrong with your car, it’s always best to consult with a professional.
Does A Misfire Always Show Up With A Check Engine Light?
No, a misfire can occur without the check engine light. The engine light only lights up when the computer detects a problem that it thinks might damage the emissions system. However, if the misfire is severe enough, it will trigger the light.
If the misfire is intermittent, the light may come on and then go off again as the problem comes and goes. Either way, if you have a misfire, it’s good to get it checked out by a mechanic to see what might be causing it.
What Are Car’s Diagnostic Codes?
A car’s diagnostic codes can tell a mechanic or dealership service department what might be wrong with your vehicle. A sensor usually triggers the car’s codes that detect an issue and then send a signal to the car’s computer. The computer interprets this signal as a code, which can be read by a mechanic using a special diagnostic tool.
Will All Cars Show A Diagnostic Code?
No, not all cars will show a diagnostic code. There are a few exceptions, though. Some older cars may have a “check engine” light, but these lights can only indicate that something is wrong – they can’t tell you what the problem is. That’s why it’s always best to take your car to a qualified mechanic if you think something is wrong.
Are All Cars Compatible With OBD2?
Most cars on the road today are compatible with OBD2, but a few still aren’t. If your car isn’t compatible with OBD2, you can do a few things to make it compatible.
- One option is to install an OBD2 adapter. It will allow you to connect your car to an OBD2 scanner.
- Another option is to buy a used car that is compatible with OBD2.
For a car to be compatible with OBD2, it must be equipped with an OBD2-compliant data link connector (DLC). Most cars manufactured after 1996 have an OBD2-compliant DLC, but some exceptions exist. For example, some European cars manufactured after 2003 may not be compatible with OBD2.
If your car is not compatible with OBD2, you can still use an OBD-II scanner by connecting it to the car’s diagnostic port. However, you will not be able to access all of the OBD2 data, and the scanner may not be able to read all of the car’s sensors.
Can The Check Engine Light Reset Itself?
The check engine light is designed to come on whenever the onboard computer detects an issue with the engine or emissions control system. When the problem is fixed, the light should go off. If it doesn’t, there are a few things you can try to reset the light.
- First, make sure that the problem that caused the light to come on in the first place has been fixed. If not, the light will just come back on as soon as you turn off the engine.
- Once you’re sure the problem is fixed, the next thing to do is disconnect the battery for about 30 seconds. It will reset the computer and turn off the light.
- If that doesn’t work, you can try a driving cycle. It means driving for about 20 minutes at highway speeds, then letting the car idle for about 10 minutes. It should reset the light if everything is working properly. If the light is still on after all of this, there may be a more severe problem, and you should take the car to a car shop.
Check Out Can Check Engine Light Turn Itself Off?:
https://axlewise.com/check-engine-light-but-no-code/
