The creation of car self-diagnostics was one of the most important advancements in the automotive industry. Its addition meant that car owners could rely on the computer in their vehicle to conduct diagnostics rather than having to understand every aspect of their automobile or make educated guesses about when anything would break down.
Early on, there was simply the check engine light, which covered practically all problems except batteries, brakes, and a few other things. More than a dozen dashboard lights are standard in modern cars, which begs the issue of what code gets activated and when.
Even though typically, it implies the vehicle will switch on and off depending on when the fault is triggered, your automobile might still send codes if the issue is intermittent, even if the check engine light is not on. Other warning indicators, such as the ABS or brake light, may also be present with the code.
The Reasons Why Some Fault Codes Do not Set Off the Check Engine Light
As we just explained, the sensors allow the ECU to monitor every action the engine is doing in real-time continuously. The charging system, camshaft, crankshaft position, ignition, air intake, and exhaust are all included in this.
Occasionally, for instance, the engine may misfire at random. Because a misfire sometimes is deemed typical, the ECU will not turn on the check engine light in certain circumstances.
The same holds for readings of a high coolant temperature and all other metrics, including the knock sensor. Additionally, if an older car’s ECU were set up to turn on the check engine light every time it detected an odd sensor reading, it would do so at least every few thousand miles.
Instead, long-term data monitoring and archiving are included in the ECU’s programming. If it notices a specific sensor giving anomalous readings too often or for a lengthy time, the check engine light will come on.
After the first occurrence, the fault code will nevertheless be retained. So even if there is no check engine light, you should scan the fault codes as soon as you observe any unusual symptoms in how the engine performs.
When it comes on, the check engine light
The check engine light activates when a specific sensor consistently returns anomalous readings within a predetermined time interval, as was previously explained. However, the check engine light will turn on right away if a specific defective component has the potential to harm the engine.
For instance, the camshaft & crankshaft position sensors might assist the ECU in detecting improper camshaft timing. The check engine light could also illuminate briefly before going off. A particular sensor could transmit readings beyond the typical range in such circumstances. A coolant temperature sensor, for instance, may provide a value of 2 volts after initially reporting readings between 0.5 and 1.5 volts.
The ECU now cuts off the temperature sensor when it detects an out-of-range reading from the sensor, and the check engine light is turned on. Once the engine is restarted, the sensor continues to provide data within the desired range. Thus the ECU does not need to turn on the check engine light.
However, the sensor is still broken, and the first moment the check engine light illuminated, a defect code was already recorded. An OBD scanner will help you locate this code.
A more significant and urgent issue is indicated if the check engine light is flashing, which may happen under specific circumstances. When one of the ignition coils malfunctions, for instance, that occurs. Additionally, the ignition coil will often return to normal after some time, precisely as it did with the temperature sensor, and the check engine light will go off. An error code is nevertheless saved once again.
Can a fault exist without a fault code or the check engine light?
We are now approaching the core issue with the OBD system. The voltage ranges and values that the sensors employ to communicate with the ECU were previously described. We will continue to explain this using the coolant temperature sensor, however. Let us assume that 0.5 volts from the temperature sensor inform the ECU that the coolant is 30C. (cold). Additionally, it tells the ECU that the coolant is 150C at 1.5 volts (overheating).
If the temperature sensor malfunctions (which holds for all other sensors), it will give the ECU erroneous information. For instance, when the engine is cold, it sends 1.5 volts to the ECU, informing it that it is overheating.
The ECU shortens the ignition time and improves the air/fuel ratio. Consequently, the automobile has less power, uses more gasoline, hesitates, runs erratically, etc.
However, the ECU will trust the temperature sensor and not record a fault code or turn on the check engine light as long as the temperature sensor delivers readings within the acceptable voltage range (0.5 to 1.5).
And the only way you can use the OBD port to identify such a problem is to purchase an application that lets you keep an eye on real-time data. In this method, you can view what a particular sensor is telling the ECU in real-time.
How to Read a Fault Code
Before discussing the various OBD2 readers, it is essential to note that certain vehicles come equipped with an inbuilt fault code scanner, such as several European GM automobiles from the early 2000s (Opel).
In such a situation, you would simultaneously depress the gas and brake pedals and hold them while starting the engine. You would then note the check engine light’s flashing pattern and get the trouble code.
Naturally, the process for obtaining this information varies across manufacturers, and once again, not all vehicles have it. Additionally, you can only read the fault codes with this system; you would require an OBD2 reader to erase them.
OBD2 Fault Code Reader
As you can see above, an interface device and a standard cable are used with an OBD2 adaptor. This is most likely the most straightforward method for reading and erasing codes. Additionally, if you get a more costly model, you will probably be able to view live data.
If you want to use it on two or more separate cars, this is the ideal solution, and you do not need any specialised computer or smartphone software. Additionally, it has a simple user interface, making it an excellent choice for beginners.
OBD2 Bluetooth Adapter
The OBD2 Bluetooth adapter has likely become the most popular choice in recent years because it is much less expensive than readers of the same kind. However, remember that you must first install the necessary programme or app on your smartphone to utilise it.
Most high-quality applications provide free light versions, but sadly, they need a one-time payment or a monthly membership. Fortunately, the light versions allow you to read and erase codes and see real-time data, which is more functionality than most drivers will ever need.
Veepeak BLE OBDCheck iOS and Android-compatible Bluetooth OBD II Scanner Auto Diagnostic Scan Tool with Bluetooth 4.0 for Car Check Engine Light Code
Do I Risk to Drive If the “Check Engine” Light Is On?
Driving is permitted even though the check engine light is solid. However, you should not drive if the check engine light blinks since it indicates a more severe problem. This also applies to other warning lights that are red rather than yellow.
How Serious Is the Check Engine Light?
No, a check engine light is not a significant problem because it will not soon cease operating or will do immediate harm to the car. However, issues that cause a check engine light may be costly and difficult to remedy, making them severe financial problems.
Can a check engine light shut off on its own?
A check engine light might indeed go off on its own. For instance, if a specific component or sensor occasionally malfunctions, the check engine light will turn on when the part ceases functioning correctly and switch off when it resumes. Additionally, the check engine light will go off on its own as soon as the issue is resolved or replaced.
Check engine light caused by low oil possible?
No, low oil is not connected to a check engine light. In addition to the check engine light, vehicles with oil level sensors have a warning light for low fat. That yellow warning light is a representation of an oiler can. A similar sign will also appear for low oil pressure, although it will be red rather than yellow.
Are all car fault codes the same?
Yes, all autos have the same problem codes. Additionally, certain brands will still emit the general fault codes even though they have unique fault codes. All of the error codes begin with the letters P0000 (powertrain), C0000 (chassis), B0000 (body), and U0000 (undercarriage) (user network).
Can a Car Throw a False Code?
No, a vehicle will never display bogus codes unless the ECU (engine control unit) is damaged. The ECU trouble codes, however, should never be interpreted literally. Instead, a fault code alone may indicate one thing, but when combined with another, it can show a third unrelated component. Because of this, it is advisable to leave fault code reading to experts when your automobile has a more severe problem.
Does a Car Fault Code Self-Repair?
No, a car’s error code will not disappear on its own. The code will be stored in the ECU memory until you manually erase it, regardless of whether you repair the damaged component or address whatever caused it. Again, however, the check engine light will go off after the underlying issue has been resolved.
Do Fault Codes Clear After Removing the Battery?
No, taking out the battery will not erase any error codes. The ECU capacitor will, however, be drained, and the ECU’s memory will be cleared if the battery is removed and then the two battery connections are connected. However, bear in mind that only older automobiles may use this technique.
Conclusion
Now that we are a bit more knowledgeable about stored fault codes, warning lights, and how sensors interact with the ECU, it should be clearer why a vehicle may have them without having a check engine light. This makes it simpler to identify any possible problems in the future, and you can be confident that if the condition that triggered the check engine light worsens, you will see a check engine light.
Last but not least, it is essential to note that sensors and other components might malfunction without producing any error codes or a check engine light. Watching live data is crucial if you observe any strange symptoms without any indications in the OBD2 system.