Diagnostic trouble codes are alphanumeric codes that indicate that something is wrong with your car. Permanent trouble codes are a bit more difficult to clear than regular codes because you cannot make them go away by removing the battery or using an On-Board Diagnostic Tool.

In this write-up, we will show you how to clear permanent codes.

How To Clear Permanent Codes?

Permanent codes were first seen in some 2009 models. From 2010 and beyond, it became an automobile software staple.

Manufacturers introduced these codes to stop people from ignoring emission-related problems. You must convince the car computer that you have resolved the underlying issue for the permanent codes to clear.

How To Clear Permanent DTC Codes

Step 1. Connect The Scanner

After addressing the problem, connect a compatible scanner to the car. Not scanners can detect permanent DTC codes. Most entry-level scanners are unable to do that.

So, you need to make sure the scanner you are using is suitable for the cause. You should easily find the information in the product description.

Switch off the engine, but keep your ignition on as you connect the scanner. If you switch off the ignition, the computer will not stay on, and the scanner will not be able to access it.

The scanner will connect the vehicle through a Diagnostic Link Connector. You should find it in the driver-side wheel well area.

Step 2. Enter OBD II Settings

Scan the car with the tool, and you will get the trouble codes immediately. Not all trouble codes are permanent DBC codes.

There could be stored trouble codes or pending trouble codes, which are relatively easier to clear. Permanent codes require a different clearing approach, but before learning about that, you must know what they look like.

Permanent codes are Mode 10 data and have dollar signs before them. Mode 10 is a stored data type that stays in the vehicle memory, but unlike other data forms, you cannot reset them without fixing the problem that is making it appear on the dashboard. If you see any trouble code that starts with a ‘$’, you have a permanent code.

Step 3. Resolve The Issue

There is no getting around permanent DTCs without dealing with the problem that’s causing them. Usually, permanent trouble codes appear when there is an issue with your emission system.

For example, you will get permanent DTCs when the EGR valve goes bad, or the catalytic converter malfunctions. You need to identify and fix the problem.

That said, in some cases, permanent DTCs might appear because of a software glitch or faulty sensors. Once you examine the exhaust system and determine that there is nothing wrong with it, you should look into these other possibilities.

It would be better to seek professional help to pinpoint the root of permanent DTCs in your car if the exhaust system is working fine.

The exact code will tell you what the problem is with your exhaust system. The P0300, for example, indicates an irregularity in the air-fuel mixture in the cylinder.

The P0442, on the other hand, points towards a leak in the vehicle’s evaporative emissions control system. You need to take action accordingly.

Step 4. Restart The Car

Allow the vehicle to cool down for a while after you complete the repairs. Take the car out for a spin half an hour later. Some manufacturers recommend that you must add 200 miles to the car’s mileage before attempting to clear the permanent codes. This ensures that all readiness monitors are working properly.

Readiness monitors identify the emission problem in the vehicle, and it needs to conduct the same test again to make sure that the issue no longer exists.

Therefore, you must give the car sufficient drive before trying to clear the permanent codes. In most cases, you can reset the permanent codes without hitting the extra 200 mile-mark.

If the car is newer, you can expect to get it ready faster for permanent DTC clearance. 6 to 7 warm-ups and an extra mileage of 100 miles could be enough.

The older the vehicle is, the longer prep time the car would need. You might have to complete as many as 15 warm cycles and drive for 200 miles to get the vehicle ready.

Step 5. Complete 3 Driving Cycles

Your vehicle’s built-in inspection system will clear the permanent codes after three successive fault-free drive cycles. Keep the scanner hooked on to find out whether the emission problem persists or not.

Run the car for about 10 minutes. The propulsion system should be active if you are driving a hybrid vehicle.

Drive the vehicle above 25 mph for five minutes. There should also be 30 seconds of the idle period when the driver lets go of the accelerator pedal, and the vehicle speed drops below one mph.

At the start of the fourth drive cycle, the monitor should stop showing the permanent codes. If the codes don’t clear, you might be dealing with other malfunctioning parts.

How To Clear Permanent OBD2 Codes

Permanent DTC codes are exclusively related to emission setbacks, but OBD2 (On Board Diagnostics 2) codes cast a wider net. They can indicate engine problems, transmission problems, and other issues. Other than emissions, an OBD2-compliant system monitors and collects vital car data like mileage, speed, etc.

So, permanent OBD2 and DTC codes are not the same. Often permanent DTC codes require quicker attention than permanent OBD2 codes because they always indicate faulty emission systems.

You would also need to follow slightly different techniques for clearing permanent DTC codes and OBD2 codes. Let’s discuss them.

Step 1. Connect The Scanner

Just like we did for the DTC codes, the starting point would be to connect a diagnostic tool to the vehicle. For DTC codes, you would need specific tools for specific vehicles.

The compatibility range is a bit larger when it comes to OBD2 code detection. But you would still need to see to it that the scanner is capable of reading OBD2 data.

The DTC diagnostic tool and the OBD2 scanner both connect to the same port. The 16-pin Diagnostic Link Connector was originally made to connect OBD2 tools, so it’s often called an OBD2 port. Put the key in the ignition and plug in the diagnostic tool. You are now all set to scan for permanent OBD2 codes.

Step 2. Scan The Vehicle

There should be an OBD/OBD2 option in your scanner. Select it to start the scanning process. Some OBD codes you will get are not permanent, like the P0171, which means there is a leak in the fuel system near the first bank of the engine. You can kick the can down the road and clear the code before making any sort of repair.

But if you get a permanent OBD2 code a la P0420, you will have to address it immediately. Otherwise, the code won’t go away, and the check engine light will stay on. If the code continues to show up on the screen despite clearing it, your vehicle has a permanent OBD2 code.

Step 3. Fix The Issue

Look up what the code means and make the necessary repairs. If it’s an emission issue, get that sorted out. The Transmission Control System might be compromised; you need to turn your attention toward that. The OBD2 codes will tell you exactly where you need to look, and when you do, fix the problem.

Step 4. Restart The Car

Leave the car for about half an hour after you are done with the repair so that it gets time to cool down. Then, take the car on the road for a drive. You would need a certain amount of drive time for the readiness monitors to return to full functioning. Once the monitors are up and running, you need to move to the final phase of the procedure.

Step 5. Complete 3 Driving Cycles

If your vehicle doesn’t detect any abnormalities in three successive driving cycles, the OBD2 codes will clear out. Make sure that the OBD2 monitor is connected to the car as you move from one driving cycle to another.

How To Clear Permanent OBD Codes

OBD and OBD2 codes are basically the same. OBD2, however, is the latest iteration of the OBD system, which was invented in the ‘80s.

So, you can clear permanent OBD codes in the same way you can clear permanent OBD2 codes. Most diagnostic tools can still read OBD codes.

How To Clear Permanent Codes Chevy

You can clear permanent codes in a Chevrolet vehicle by following the methods we discussed above. The trouble codes could be a bit different in a Chevy, so look up the Chevrolet trouble code list to avoid confusion. (Chevrolet Fault Codes pdf)

Final Words

Learning how to clear permanent codes will not make you able to reset your car’s computer without fixing the actual problem. Find out what’s wrong, sort it out, and the annoying engine light will finally go off.

Author

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Mark Williams

Founder and Author at Theautomobily

Mark Williams is the founder and author of Theautomobily located in Tucson, AZ. As a Mechanical Engineer,He has 15 years of experience in the automobile industry. Mark's deep understanding of various types of vehicles such as UTVs, ATVs, cars, Trucks, and lawnmowers which allows him to provide valuable insights and information.

How To Clear Permanent Codes For Improved Car Performance