Mode 06 Diagnosis

One of the keys to understanding Mode $06, or getting the most out of your scan tool, is to understand what the different modes are and how they are used. How many modes are there? There are 9 modes of scan tool operation. Many technicians have been using 4 or 5 modes for 20 years. Each of the 9 modes is beneficial and important to understand when it comes to diagnosing today’s vehicles. SAE document J1979 lays out the definitions of the on board diagnostic system or OBD II. The document also separates scan tool operation into 9 modes.

The Nine Modes of Scan Tool Operation:




Mode 1

Data Stream

Displays sensor values and calculated values. This mode is generally offered on every scan tool, although some will offer more info than others.

Mode 2

Freeze Frame Data

This is information (data) that was captured when a fault occurred

Mode 3

Diagnostic Trouble Codes

The 5 digit fault code which corresponds to a definition (which may or may not be displayed). PO codes are generic, whereas P1 codes are manufacturer specific. Some scan tools will not display all P1 codes.

Mode 4

Clearing DTCs and Freeze Frames

Erases memory codes, Freeze Frame data, Mode $06 results, Monitors, and sometimes Adaptive Strategies.

Mode 5

Oxygen Sensor Monitors

This mode displays oxygen sensor test results and the parameters used. May be useful.

Mode 6

Non-continuous Monitors

Displays results of Non- Continuous Monitors, Misfire Monitors, and the parameters used. Helpful in diagnosing intermittent problems, no code issues, and eliminating comebacks.

Mode 7

Pending Trouble Codes

First trip failures are stored here before they mature into a DTC and illuminate the MIL (Mode 3).

Mode 8

Bi-directional Controls

Allows the user to turn components ON or OFF, run self tests, and relearn procedures.

Mode 9

Vehicle ID

Displays vehicle specific information – VIN, Cal ID, etc.

How Do These Modes Work Together?

  • Step 1 – Once the enabling criteria is met, the PCM will run the Monitor.
  • Step 2 – The PCM will store the results in Mode $06
  • Step 3 – If the Mode 06 result is Fail, a pending code may be stored in Mode $07 and Freeze Frame Data is stored in Mode $02.
  • Step 4 – The next time enable criteria is met, the PCM will run the Monitor again.
  • Step 5 – The results are stored in Mode $06.
  • Step 6 – If the Mode 06 result is Fail, a pending code may be set and Freeze Frame Data is stored in Mode $02.
  • Step 7 – If the pending slot is already occupied by the same code, it now stores the code in Mode $03 and turns ON the MIL.

Mode $06 Details

Mode $06 was originally written to be an engineering tool, rather than to be used by a technician for diagnosis. Consequently, it took a while for aftermarket scan tool manufacturers to incorporate the conversion and display of Mode $06 values . In its native format, Mode $06 results are in hexadecimal format. This will be discussed in more depth later there are several different “layers” of Mode $06. The top layer is basically a Pass/Fail statement. This tells the technician/user the results of the last test. The next layer tells us the actual results of the test, along with the specifications of the test. For example: Let’s say that you recently took an ASE certification test. Several weeks later you get a letter in the mail that says congratulations you’ve passed. It tells you that in order to pass you had to correctly answer between 75% and 100% of the questions, and you scored 78%. You know that you passed, but barely, and if some action isn’t taken, next time will be a failure. On the other hand, the letter may have contained bad news. In this case, it would be helpful to know how close you were to passing. Relating this back to a vehicle, let’s say a technician replaces a component, clears the DTC, and road tests the vehicle until the Monitor runs and passes. Mode $06 test results can be used to see how well the component performed. If the Monitor only passes by a slim margin, the vehicle may return later with the same failure. This is where Mode $06 can be helpful by going beyond the Pass/Fail layer. Mode $06 can also be used where the vehicle has a diagnostic trouble code. The technician can verify that the Monitor has run, and then look at the Mode $06 results, to see if it failed or passed and by what margin.

Here are some tips:

  • Beware of substitute values. If memory DTCs have been recently cleared, pre CAN Mode $06 will insert a value, which will be updated once the Monitor has run. Don’t get misled by a false path chasing a substitute value.
  • An example of using Mode $06 on a vehicle with a DTC would be a Ford with an EVAP leak code. It is always important to determine when the DTC set before committing time looking for leaks. Mode $06 can be used to look at the results of the last EVAP test. If it failed, the technician knows that the problem probably still exists.
  • Since Mode $06 isn’t live data, the results aren’t always automatically updated on the scan tool. Most times it will be necessary to hit the Refresh button, or exit out and reenter Mode $06 to get the updated results. Sometimes it is necessary to cycle the key OFF and ON again.


When looking at Mode $06 data in its raw format, the technician will see the label TID and CID. These acronyms stand for Test Identification and Component Identification. The TID identifies which OBD II system is being tested. The CID is the display of the specific component within the tested system. Many scan tools will display these definitions for the user, however some do not. When dealing with pre-CAN Mode $06, TIDS and CIDS change from year to year, and between manufacturers. Make sure to look up the definition for the vehicle you are repairing.

mode06 ford example

Hexadecimal Conversions

As stated earlier, Mode $06 was originally written to be an engineering tool, rather than a technician’s guide. This is why data has been displayed in hexadecimal, the universal language used in math, computer, and engineering industries. A hexadecimal number is preceded with the $ symbol. The hexadecimal system doesn’t contain negative values. It is based on a numbering system of 1-16, whereas the numbering system that we are familiar with is based on 1-10. Relating hexadecimal numbers to decimal numbers is accomplished through use of a conversion table. 1-9 are the same but 10=A, 11=B, 12=C, 13=D, 14=E and 15=F. This is a typical Mode $06 result. Common sense would dictate that the test value is greater than the minimum limit, bringing a technician to the assumption that the component under test is within the limits. However, before making this assumption the data must be converted. The test value of $02DC converts to 732 in decimal numbering. However, that is not the end of the conversion. In order to finish the conversion, the information must be obtained for the specific vehicle, and its TIDS, and CIDS. This example was from a 1997 Ford Windstar. Using service information, we can determine that TID $01 is for the 02 voltage amplitude and voltage threshold, and CID $11 indicates Bank 1 Sensor 1.

Help with Conversions

Many of today’s scan tools perform the conversion for us. Even in the rare case that your scan tool displays the hex code, rather than the decimal value, the technician can use the calculator application that comes on every Windows PC to make the conversion. Click Start, select accessories and choose calculator. When the calculator opens, select Scientific from the View menu. Click the button next to Hex. Now the Hex values can be entered. Click the button next to Dec to complete the conversion.

Obtaining Conversion Information

The best, most reliable sources for Mode $06 information are the individual manufacturer’s websites. Many OEMs include the Mode $06 charts in the free part of their website. It is always important to verify which model year and system you are repairing, because the TID or CID can be different from year to year. For example on a 1997 Ford, TID $21 is defined as EVAP system initial tank vacuum but in 2002 it indicates Bank 1 Catalyst index ratio and maximum limit. Use caution, just because a scan tool displays the definitions and does the conversions for you, doesn’t always mean they are correct. Just to be safe, it is a good idea to go to the websites to find the correct definition, especially if the data does not make sense. The easiest way to find this information is through NASTF( This site has a listing of all the manufacturer’s websites along with some other useful information.

This post was written by: Martin Hand


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Martin Hand

About Martin Hand

ASE Certified L1 Advanced Mastertech. Martin Hand has over 15 years experience in Asian and European Import Auto Repair. Specializing in electrical diagnosis, engine performance, AT/MT transmission repair/rebuild. Martin is also pursuing a degree in Computers Science & Information Systems starting at Portland Community College while he plans to transfer to OIT. Certified in Java application level programming, experienced with other languages such as PHP, Ruby, JavaScript and Swift. Martin has future plans of automotive diagnostic software development.


  • Manoj Pandey says:

    How do I get the Min and Max threshold,the limits for Mode $06 values which set the OBD2 codes?
    Is it available somewhere?

    • Martin Hand Martin Hand says:

      the values are specific for each manufacturer and have to be obtained through service manuals. Alldata and MitchellOnDemand have some values for some manufacturers but it really depends on the vehicle. German and Asian Imports use different terminology than domestic vehicles so it can be confusing and misleading. If your in the repair field as a technician then just start comparing values between same vehicle types and you’ll start to become familiar with them overtime. Only in rare cases do I use them as a diagnostic tool.

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