How to Clear Codes on a Car with Scanner? Will It Actually Help?

You are driving to work, and the check engine light suddenly appears on the dash. You are concerned something is wrong with the engine. After all, what else would cause the check engine light to pop on the dash unless something was the matter with the engine? You decide to report to work and sort the issue come the weekend. When you start the engine after a long day at work, you notice the check engine is no longer there. Come the following morning, and the check engine light appears again.

Clearing the DTCs highlights

• Difficulty level:Low
• Needed scan tools:Professional tool or app
• Additional equipment:No other tools needed
• Timeneeded:10-15 minutes
• Price in a shop:$150 - $250
• DIY repair:Possible

What are codes?

Your car is equipped with a computer unit that communicates with the vehicle systems and components. The vehicle computer is commonly referred to as the ECU or the engine control unit. The various systems in the vehicle monitor or control the vehicle's functions, and the ECU plays a critical role in this.

When a particular system on the vehicle, such as the engine oil pressure or the ABS, malfunctions, the ECU records such and reports to the driver via the dashboard. An on-board diagnostics (OBD) system is incorporated into the ECU, which records and reports all the problems the vehicle systems report to the ECU. These problems are reported as error codes. The OBD system, therefore, stores all the codes (issues) the vehicle has.

The diagnostic trouble codes (DTC) are stored and can only be read using a compatible scanner. Even though vehicles had ECUs that stored codes even in the 80s, it was only in 1994 that the reading of the trouble of codes became universally accepted.

The on-board diagnostic scanner was introduced in 1981. This scanner was referred to as an OBD-I. Reading trouble codes required a person to have a different OBD-I for every model they wished to diagnose. In 1994, the OBD-II was introduced, where the reading of trouble code systems was standardized. An OBD-II can be used to read trouble codes in all makes of cars. However, small variations vary in OBD-II scanners since every scanner should fit in any of the five protocols.

What to know before you clear codes on a car with a scanner

Whenever a warning light appears on the dashboard, it is possible to diagnose the problem without necessarily going to a mechanic. With the advent of OBD-II scanners, it was almost impossible to own a scanner as a car owner because they were very expensive. Over time, cheaper options have entered the market, and you can buy a simple OBD-II online for as low as $20.

The cheap OBD-II scanners are cheap are limited in what they can read and how many diagnostic results they can provide you. In many instances, they are non-specific in their reading of the DTC. The more expensive ones, mostly used by professional mechanics and at dealerships, are more thorough in their diagnostic analysis. It is, therefore, possible to find that your home scanner is giving you a certain code, but when you go to a mechanic, additional codes pop up, some of which are unrelated to what your scanner indicated.

When you connect the OBD-II scanner to the carport in your car, you are able to access the DTC where the codes are stored. You will be able to read the codes on the scanner. The serialization of the codes is universal, and you shouldn't have trouble reading the codes. The codes are alphanumeric; for example, P0101.

• P - Powertrain. This includes the transmission, engine, and fuel system.
• C - Chassis. This will include braking, steering, and suspension.
• U - Network. Refers to onboard computers and systems.
• B - Body. It mainly refers to parts, including the passenger compartment, such as safety belts.

How to clear codes on car

As described above, you can use a cheap OBD-II scanner to help you with the diagnosis of the issues affecting your car. You can use the same scanner to clear codes so warning lights on the dash, such as ABS or check engine lights, disappear. The procedure of clearing codes is similar though not exactly the same, in various OBD-II scanners. Here is how to do it:

• Get a compatible OBD-II scanner. You may find some scanners are incompatible with some vehicle systems.
• Connect the scanner to the OBD port, which is mostly located near or under the steering on the driver's side. This is the same port used for state or government vehicle inspections.
• Switch the ignition to the ON position. Press the button twice for cars with the Start/Stop ignition without depressing the brake.
• Wait for the OBD-II scanner to establish a connection. Once the connection is established, the scanner will show 'Read.' Press 'Read,' and scanning will commence.
• The issues causing the warning lights will show on the scanner in the form of trouble codes. The vehicle records and stores codes in a standardized format, making it possible for all OBD-II scanners to read them. The codes are alphanumeric and will start with a letter followed by around four numbers.
• Once the scan is completed, take note of all the error codes the scanner lists. Decode the codes so that you can identify the problem, which then allows you to replace, repair or calibrate whatever is causing the problem.
• When the problem causing the ECU to throw a code has been resolved, it is time to clear the error code in the ECU using the scanner. Some OBD scanners ask you to 'erase' the code, while others ask you to 'clear.'

Once the error code has been cleared, the resulting warning light, such as the check engine light, will disappear from the dashboard. You should, however, confirm that the warning light has been eliminated completely by switching 'off' the ignition and then switching the engine ON. If the problem has been resolved, the OBD-II scanner will not read an error code the second time you switch the engine ON for the second time.

When can you clear codes on the car

• When you see a check engine light on the dashboard, you can tell what is wrong by connecting an OBD-II scanner which will give you a code relating to the problem. In our earlier stated case where the check engine light appears intermittently, you might be tempted to clear the codes causing the light to appear.
• When you use an OBD-II scanner, you are required to follow a certain procedure. Normally, after reading the error codes in the OBD, you will be able to locate the source of the problem and, after that, be able to repair or replace the malfunctioning component or system. After working on the problem, it does not mean the check engine light or other warning light will automatically disappear. You will need to clear the related code so that the check engine light goes away and to show that you have resolved the problem.
• There are error codes that are recorded, and they will cause a check engine light or some other warning even after you resolve the problem. A good example is when the engine misfires once or when you inadvertently fail to fit the fuel cap. The engine check light will pop up because of either of the problems and will remain illuminated even after you correctly fit the fuel cap. This makes it necessary to clear the related codes.
• There are unscrupulous mechanics out there who will cheat you into thinking that they have resolved a certain problem while they haven't. They will attach the OBD-II scanner and clear the codes without resolving the problem. While this can be done under certain circumstances, it should be avoided as further damage to the car can occur without you knowing.

Will clear codes with a scanner help?

Clearing trouble codes is necessary when trying to resolve issues causing the codes to appear in the first place. As stated earlier, in resolving an issue using the OBD scanner, you are supposed to identify 'clear' the codes once you are satisfied you have resolved the specific issue causing the code.

Clearing a trouble code without first resolving the underlying problem is possible. However, in many circumstances, clearing or erasing a code and failing to rectify the faulty system or component often leads to tears down the road. Once you clear a check engine light, for example, it does not solve the problem even if you trick the ECU you have. More often than not, the damage deteriorates, and the vehicle's safety becomes compromised.

Conclusion

As seen in this article, clearing error codes with the scanner in the car is necessary if you have resolved the problem causing the codes to be stored first. We have also seen that clearing the codes without first dealing with the cause does not help, and in many cases, further damage happens when you continue operating the vehicle. Clearing the codes will be of help if the reason it appeared was forgetting to tighten the fuel cap, which causes the CEL to appear.