Unlock Advanced Car Diagnostics with Android OBD2 Mode 6

For car enthusiasts and those keen on maintaining their vehicle’s peak performance, understanding the intricacies of onboard diagnostics (OBD2) systems is crucial. While basic OBD2 functions can retrieve generic diagnostic trouble codes (DTCs), Android Obd2 Mode 6 takes automotive diagnostics to a deeper level. This advanced mode allows you to access detailed component and system monitoring data, offering insights beyond standard error codes.

Mode 6, as defined in SAE J1979 standards, is specifically designed for “Diagnostic data available by request – On-Board Monitoring Test Results for Continuously and Non-Continuously Monitored Systems.” In simpler terms, it provides access to the results of on-board diagnostic tests for various emission-related components and systems. This data is invaluable for pinpointing potential issues before they trigger a standard DTC or escalate into more significant problems.

Let’s delve into an example of how to interpret Mode 6 data using an Android OBD2 app. Imagine you’ve run a Mode 6 query, and you receive a data stream like this:

7E8 10 37 46 01 01 0A 0E 66 7E8 21 0E 66 0E 66 01 02 0A 7E8 22 0E 66 0E 66 0E 66 01 7E8 23 07 0A 00 00 00 00 0C 7E8 24 D8 01 08 0A 1D 70 13 7E8 25 18 22 90 01 09 10 00 7E8 26 78 00 78 05 F0 01 0A 7E8 27 10 00 00 00 00 00 00

This raw data might seem daunting, but breaking it down reveals valuable information about your vehicle’s health. After removing the header and multiframing information, we can organize the data into a more readable format:

01 01 0A 0E 66 0E 66 0E 66 01 02 0A 0E 66 0E 66 0E 66 01 07 0A 00 00 00 00 0C D8 01 08 0A 1D 70 13 18 22 90 01 09 10 00 78 00 78 05 F0 01 0A 10 00 00 00 00 00 00

This data represents six test results, each comprised of 9 bytes. Let’s focus on the fourth test result for a detailed explanation:

MID TID UASID VHI VLO MINHI MINLO MAXHI MAXLO
01  08  0A    1D  70  13    18    22    90

• MID (Monitor Identifier) 01: This indicates the specific monitor being tested. In this case, 01 corresponds to the “exhaust gas sensor monitor bank 1 – sensor 1” according to SAE J1979(DA). This tells us we are looking at data related to the upstream oxygen sensor on bank 1.

• TID (Test Identifier) 08: This specifies the particular test being performed. 08 signifies “Maximum sensor voltage for test cycle.” We are examining the maximum voltage reached by the oxygen sensor during a test cycle.

• UASID (Unit, Scaling, and Accuracy ID) 0A: This defines the units and scaling applied to the test values. 0A indicates “Voltage” and “0.122 mV per bit unsigned.” The voltage values are scaled with a resolution of 0.122 millivolts per bit.

• VHI/VLO (Test Value High/Low Bytes) 1D 70: These two bytes combined represent the actual measured test value. To get the voltage in millivolts, we perform the calculation: (0x1d * 0x100 + 0x70) * 0.122 = 919.392 mV. The maximum sensor voltage recorded during the test cycle was approximately 919 mV.

• MINHI/MINLO (Minimum Limit High/Low Bytes) 13 18: These bytes define the minimum acceptable limit for the test. Calculating this limit: (0x13 * 0x100 + 0x18) * 0.122 = 596.336 mV. The minimum allowed maximum sensor voltage is about 596 mV.

• MAXHI/MAXLO (Maximum Limit High/Low Bytes) 22 90: These bytes define the maximum acceptable limit. Calculation: (0x22 * 0x100 + 0x90) * 0.122 = 1079.456 mV. The maximum allowed maximum sensor voltage is approximately 1079 mV.

In this example, the measured maximum sensor voltage (919 mV) falls within the acceptable range defined by the minimum (596 mV) and maximum (1079 mV) limits. Therefore, this particular test for the exhaust gas sensor has passed.

OBD2 Expert Component Monitoring Mode 6 Diagnostics

Android OBD2 apps, especially those designed for in-depth diagnostics, are increasingly incorporating Mode 6 data interpretation. These apps often handle the complex data decoding and calculations for you, presenting the results in a user-friendly format, like the screenshot above from an OBD2 iOS app which is also available on Android. By leveraging Android OBD2 Mode 6 capabilities, you can gain a more comprehensive understanding of your car’s engine performance, monitor sensor health, and proactively address potential issues, ensuring optimal vehicle longevity and efficiency.