What is Mode 6?

Mode 6 is one of the modes defined by EPA (Environmental Protection Agency) and SAE (Society of Automotive Engineers.) It’s a part of OBD2 (On-Board Diagnostics) system that contains a list of advanced test results. These test results are very useful when you perform emission related diagnostics.

Mode 6 on Older Scan Tools

Mode 6 has been around for many years, but technicians have not made much use of it because not all scan tools can access to the test results. And even if scan tools supported Mode 6, they may have showed only hex codes which have to be converted common decimal values for people to understand. They don’t even tell what test results on the display (instead they are showing MID$01, $02…) So, it has been difficult to use Mode 6 with older and budget type of scan tools. However, thanks to advancing technology, there are more and more versatile scan tools on the market with reasonable price, Now you don’t need to spend thousands of dollar for scan tools to use Mode 6.

Non-DTC Diagnostics with Mode 6

Mode 6 is useful for solving emission related problems even when there are no DTCs (Diagnostic Trouble Codes.) Vehicle’s computer won’t turn on check engine light as long as sensors and components are operating within an acceptable range. But when one of them is close to its limit, it may affect your car’s driveability even if an issue is not big enough to turn on check engine light. For example, if a car has no power under the load. You suspect it is misfiring, but there are no trouble codes. Check mode 6; it shows a misfire count. You may see only one cylinder has large number (misfire counts.) The number may not be large enough to trigger check engine light, but it is enough to make you feel a lack of power.

It can also be used to know if a repair you just finished has been successful. Many aftermarket parts have shorter life spans than ones from manufacturers. The problem is they are not defective when installed, but after a little while they become bad and set the same code as a car had before. These potential problems can be spotted by viewing Mode 6. For example, a car has P0420 Catalyst System Below Efficiency, and then you replaced a catalytic converter with an aftermarket one. Let’s say this aftermarket converter was so poor quality that it would eventually turn on check engine light with the same code P0420. But it didn’t turn on right away. The first test result had been passed, and maybe the second, and even third one, too. But the fourth test was failed, and finally, turn on check engine light. If you kept looking the test results in Mode 6 since replacement, you might have seen a test result (not only pass or fail but also a value) was close to the threshold. Then, you could have determined that the converter was defective much earlier despite its test result.

OBD Scan Tools that supports Mode 6

Today, many scan tools support Mode 6. However, budget handheld scan tools are still hard to navigate. You may have to press up/down buttons many times to reach test results. You may also need to translate hex code for yourself. Scan tools with large color display don’t have such problem, but they are surely expensive. What I recommend is a small adapter called BlueDriver. It’s a Bluetooth-enabled adapter that is plugged into an OBD2 port. With an app, your smartphones or tablets become sophisticated scan tools. It has all essential features of scan tools and more. In Mode 6, you can see many test results on one screen. Test values are already translated, and you can see names of tests by tapping on test ID. Click here to see more details.

Again, Mode 6 is very useful, but it’s been overlooked because not many scan tools supported it. Now that many scan tools support it, you have to use it.

OBD2 Mode 6 Diagnostics
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