Rick's Free Auto Repair Advice

What is Mode $06?

How to use Mode $06 to diagnose a problem

OBDII diagnostics have 9 modes. Mode $06 is one of the best for finding problems. When OBDII diagnostics were designed, the developers came up with nine modes.

Mode $01: Monitor Status and Current Data

Mode 1 tells you the status of the rediness monitors. Each readiness monitors is associated with a system or component on the car that affects emissions. Readiness monitors are either continuous or non-continuous.

Continuous monitors are the Comprehensive Component monitor, the Misfire monitor and the Fuel monitor. All the other readiness monitors are non-continuous.

Each readiness monitor conducts a battery of tests to determine the health of that system or component. The readiness monitor simply tells you whether all of the tests for that monitor have run to completion.

Mode $02: Freeze Frame

Mode 2 is basically a recording function that stores the available data parameter I.D.s (PIDs) that are in the ECM at the same time it set a DTC. For example, the freeze frame data from a misfire trouble code can tell you the RPM, engine load, fuel trims and sensor readings that were present when the code set.

Mode $03: Stored Diagnostic Trouble Codes

Mode 3 is simply a stored list of trouble codes that have set and turned on the check engine or Malfunction Indicator Lamp (MIL). It’s what most users think a scan tool is for. Once a code has set, the ECM will continue testing. If the continuous testing shows that a once failed code now pass for three consecutive tests, the ECM will turn off the MIL.

However, the code will continue to be stored in Mode 3 as a history code. After a specified number of warm-up cycles with no recurrence, the code will be erased from memory.

Mode $05: Oxygen Sensor Monitor Test Results

Mode 5 contains the test results the ECM stored for verifying the proper operation of the oxygen sensors.

Mode $06: Non-continuous Monitor Test Results

Mode 6 is lists the individual tests and their results for every non-continuous monitor that has reached the threshold to set a trouble code. Most aftermarket service information systems list the test identifications and descriptions, making Mode 6 more friendly and more valuable.

Mode $07: Continuous Monitor Test Results or pending codes

Mode 7 is where you’ll find the records for trouble codes for systems or components that have failed once and require two fails to actually set the code. So, in effect, the trouble code is “pending” just waiting for a second fail. If you find a pending code, look up the freeze frame data for that pending code and then recreate the driving conditions to try and force a second failure.

Mode $08: Request Control Of Onboard Systems

In OBDII, only the EVAP system works with Mode 8 and then only on some models. Mode 8 allows you to command the EVAP system to seal itself by closing the canister vent valve, allowing you to then vacuum or pressure test the system for leaks.

Mode $09: Vehicle Information

Mode 9 provides the Vehicle Identification Number (VIN), and the ECM’s calibration information. This important data to determine whether the software in the vehicle is up to date.

How to use Mode $06 information to get a diagnosis

Let’s say your car maker requires a 500 misfire threshold on a single cylinder before it sets a cylinder related misfire code. The vehicle isn’t running right and you don’t have a check engine light or any stored or pending trouble codes. That’s where you head to Mode $06. Examine the data for each cylinder and see which cylinders have misfires and how many are stored.

Mode $06 is valuable for more than just misfire codes. Mode $06 also stores all the accumulating data for these components and systems—data that hasn’t quite reached the threshold to set a trouble code.

Exhaust Gas Sensor Monitor
Catalyst Monitor
EGR Monitor
VVT Monitor
EVAP Monitor
Exhaust Gas Sensor Heater Monitor
Heated Catalyst Monitor
Secondary Air Monitor
Fuel System Monitor
Boost Pressure Control Monitor
NOx Adsorber Monitor
NOx/SCR Catalyst Monitor
Misfire Cylinder Data
PM Filter Monitor

©, 2019 Rick Muscoplat

Posted on by Rick Muscoplat

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