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What Is Mode 6 on a Scan Tool?

Last Updated on June 2, 2025

If you’re wondering, what is Mode 6 on a scan tool, you’re not alone. Many car owners and even seasoned DIY mechanics have used OBD2 scanners to pull diagnostic trouble codes (DTCs), reset the check engine light, or view live sensor data—but Mode 6 remains a mystery for most. It’s hidden, often underutilized, but can be your secret weapon for catching vehicle issues early—before they become expensive repairs.

In this comprehensive guide, I’ll break down everything you need to know about Mode 6, including how I discovered it, how it works, why it matters, and how it helped me solve real-world car problems. Whether you’re using a basic OBD2 scanner or a professional-grade tool, learning about Mode 6 could take your diagnostics to the next level.

The Day I Discovered Mode 6 on My Scanner

Like many car enthusiasts, I used to rely on the typical features of my scan tool: reading engine codes, clearing DTCs, and watching live data streams. But one day, while troubleshooting a rough idle on my Honda Accord, I decided to explore every menu. That’s when I found a section labeled “Mode 6.”

Out of curiosity, I clicked on it. Instantly, I was greeted with a wall of raw data—hexadecimal codes, Test IDs (TIDs), and Component IDs (CIDs). It looked confusing, but it also looked important. I had no clue what any of it meant… yet I knew I’d found something powerful.

That discovery led me down a rabbit hole of research—and changed the way I diagnose problems forever.

What Is Mode 6 on a Scan Tool? (Quick Definition)

Mode 6 is part of the OBD2 standard diagnostic modes and allows you to view non-continuous monitor test results. These are background tests your car’s ECU runs on key components like the catalytic converter, oxygen sensors, EGR valve, and misfire detection—often without triggering a Check Engine Light.

Unlike Mode 3 (which shows stored trouble codes), Mode 6 lets you see how close a component is to failure based on precise test data. That makes it an essential tool for early detection and preventive maintenance.

Why Is Mode 6 Important for DIY Car Diagnostics?

Most people wait until their Check Engine Light (CEL) comes on before taking action. But by then, the issue has often worsened. Mode 6 helps you diagnose issues before they hit that threshold. It bridges the gap between feeling something is off and identifying the root cause—even when no DTC has been triggered yet.

Here’s a great example.

Real-Life Use Case: How Mode 6 Helped Me Catch a Misfire Early

Back to that rough idle issue on my Accord—none of the usual checks (spark plugs, coils, vacuum leaks) gave me any clues. But when I pulled up Mode 6 data, I found that one cylinder was consistently failing its misfire monitor test, even though no DTC had been triggered.

I swapped the coil and plug to another cylinder—and the misfire followed. Thanks to Mode 6, I was able to catch and fix the problem before it turned into something bigger (like damage to the catalytic converter or failed emissions testing).

How Mode 6 Data Is Displayed

Depending on your scan tool, Mode 6 data might look something like this:

  • TID: $01
  • CID: $0B
  • Test Description: Catalyst Efficiency
  • Minimum Value: 0.02V
  • Maximum Value: 1.00V
  • Current Value: 0.95V

This tells you that your catalytic converter is still within spec, but getting close to the edge. If that number went over 1.00V, it might’ve triggered a code like P0420.

🔗 Related Post: How to Use an OBD2 Scanner to Read Engine Codes

Understanding Mode 6 Test IDs (TIDs), CIDs, and Data Values

If you’re still wondering what is Mode 6 on a scan tool, this is where the mystery starts to unfold. Mode 6 displays data using Test IDs (TIDs) and Component IDs (CIDs), which represent specific diagnostic tests and the components being tested. While the values might look like meaningless hexadecimal codes at first, they provide powerful insights once decoded.What Is Mode 6 on a Scan Tool

What Are TIDs and CIDs?

  • TID (Test ID): Refers to a particular diagnostic test being run.
  • CID (Component ID): Refers to the component associated with that test.

For instance:

  • TID: $01, CID: $0B = A test for catalytic converter efficiency.
  • TID: $02, CID: $0C = A test for O2 sensor switching response.

These IDs are standardized in the OBD2 system but may vary slightly depending on the vehicle manufacturer and model.

Typical Test Values Explained

Each Mode 6 entry usually includes:

  • Minimum value (threshold to pass)
  • Maximum value (threshold not to exceed)
  • Measured (Current) value from the vehicle

Let’s break down an example:

TID: $01, CID: $0B
Test: Catalyst Efficiency
Minimum: 0.02V, Maximum: 1.00V
Current: 0.95V

This means the catalyst is working within acceptable parameters—but it’s getting close to failing. If this number crosses 1.00V, a code like P0420 (Catalyst System Efficiency Below Threshold) might be stored.

🔗 Related Post: P2a01 Code Guide: Causes, Symptoms, and Fixes

Why Mode 6 Data Isn’t Always Easy to Read

Here’s the catch: not all scan tools interpret Mode 6 data clearly. Some may show everything in raw hexadecimal values (like 0x03FF), which you’ll need to convert or look up manually. More advanced or professional-grade scan tools simplify this by:

  • Translating test descriptions
  • Labeling values clearly
  • Using color indicators (e.g., red = fail, green = pass)

If you’re using a basic scan tool, you may need to cross-reference TIDs and CIDs with your vehicle’s service manual or community forums like:

  • OBD-Codes.com
  • ScannerDanner forums
  • Vehicle-specific subreddits

Case Study: Intermittent Acceleration Issue on a Toyota Camry

A few months after my Honda discovery, my wife’s Toyota Camry started suffering from poor acceleration and a slight rotten-egg smell from the exhaust. No check engine light came on. But I remembered Mode 6.

I plugged in the scanner, checked Mode 6, and found that the downstream oxygen sensor was operating at the very edge of its acceptable range. Other diagnostic modes (like Mode 1 or Mode 3) didn’t show anything unusual.

After replacing the sensor, the performance issue disappeared—and I avoided a costly dealership diagnostic fee.

Important: Not All Vehicles Support the Same Mode 6 Tests

Some vehicle makes and models are more generous than others when it comes to Mode 6 data:

  • Ford and GM: Very detailed Mode 6 outputs
  • Toyota and Honda: Decent support, but sometimes use manufacturer-specific PIDs
  • BMW and European cars: Often more restricted or encoded

🔗 Want to diagnose Ford vehicles better? Check our guide: Best OBD2 Scanners

Scan Tools That Support Mode 6 – What You Need to Know

By now, we’ve uncovered what Mode 6 is, how to interpret the values, and why it’s so useful. But none of that matters unless your scan tool can read and display Mode 6 data properly. Not all OBD2 scanners are created equal—some won’t show Mode 6 at all, while others might display unreadable raw hex values.

Let’s explore the types of scan tools that do it right and help you make smarter buying decisions.

Do All OBD2 Scanners Support Mode 6?

No. That’s one of the biggest mistakes new users make—assuming every scan tool can access and decode Mode 6 data.

Here’s a breakdown of what to expect:

Scanner Type Mode 6 Support
Cheap code readers ($10–$30) ❌ Usually don’t support Mode 6 or display unreadable data
Basic Bluetooth apps ⚠️ May access Mode 6 but show raw hex codes
Mid-range handheld scanners ✅ Often show simplified Mode 6 data
Professional-grade tools ✅✅ Full Mode 6 decoding with plain English labels

🔗 Related Review: 8 Best Launch Scan Tool Reviews in 2025

Recommended Scan Tools That Handle Mode 6 Well

If you’re serious about using Mode 6, here are a few scanners we’ve tested that do a great job:

  1. Innova 5610 – Excellent Mode 6 support with labeled data and live testing features🔗 Innova 5610 Review
  2. Autel MaxiCOM MK808 – A powerful mid-range scanner that simplifies Mode 6 values🔗 Autel MK808 vs MX808 Comparison
  3. BlueDriver Bluetooth Scanner – Offers good Mode 6 data decoding through its mobile app
  4. Launch CRP129E – Reliable and user-friendly for both Mode 6 and live data viewing

If you already own a scanner, check your model’s manual or menu for a section labeled “Mode $06” or “On-Board Monitor Test.” If it’s missing or poorly displayed, consider upgrading.

Important Tip: Use the Scanner’s Manual and Software Tools

Even with a good scanner, interpreting Mode 6 data can still be tricky. That’s why I recommend:

  • Reading the scanner’s manual – Many tools provide decoding charts and TID explanations.
  • Using scanner software – Some manufacturers offer PC/Mac software that makes Mode 6 data easier to analyze.
  • Exporting Mode 6 data – I often export readings to a spreadsheet and track trends over time.

🔗 Related Resource: How to Choose the Best OBD2 Scanner for Your Needs

Real-World Example: Catching EGR Flow Problems with Mode 6

One of my favorite Mode 6 saves happened on a Chevy Malibu. The car didn’t have any CELs, but it was stalling intermittently. I pulled up Mode 6 and found failed EGR flow readings—just slightly outside the range.

Cleaning out the EGR valve and passages fixed the issue. Without Mode 6, I’d have gone through a costly and frustrating parts-swapping process.

Mode 6 vs Other OBD2 Diagnostic Modes – What’s the Difference?

To really understand what is Mode 6 on a scan tool, it’s helpful to see how it fits into the larger diagnostic system of OBD2. Mode 6 is just one of several modes available on modern scan tools—and each serves a different purpose.

Let’s compare Mode 6 with the other OBD2 modes to help you use your scanner more effectively.

Overview of OBD2 Diagnostic Modes

Mode Purpose
Mode 1 Live sensor data (RPM, speed, fuel trims, etc.)
Mode 2 Freeze frame data (snapshot at time of fault)
Mode 3 Stored diagnostic trouble codes (DTCs)
Mode 4 Clear/reset DTCs and MIL (Malfunction Indicator Light)
Mode 5 Oxygen sensor test results (specific to older OBD2 systems)
Mode 6 Non-continuous monitor test results (background tests for key components)
Mode 7 Pending trouble codes (issues that haven’t yet turned on the check engine light)
Mode 9 VIN, calibration ID, and other vehicle information

🔗 See Also: How to Read obd2 freeze frame data?

Why Mode 6 Is Unique

Unlike Modes 3 and 7, which rely on stored or pending codes, Mode 6 shows raw test results, letting you:

  • Catch problems before codes are set
  • Identify borderline component failures
  • Make preventive repairs without guesswork

In many cases, Mode 6 can act as your early warning system, giving you critical insights that no warning light will.

How to Use Mode 6 With Other Modes

If you really want to step up your diagnostics, use Mode 6 in conjunction with other OBD2 modes. Here’s how:

  • Step 1: Start with Mode 3
    Pull stored DTCs to see if there are any obvious faults.
  • Step 2: Check Mode 7
    Look for pending codes that haven’t triggered the CEL yet.
  • Step 3: Use Mode 1
    Monitor real-time sensor data to identify trends or inconsistencies.
  • Step 4: Dive into Mode 6
    Analyze test results for non-continuous monitors. These may include:

    • Catalyst efficiency
    • EGR performance
    • Misfire counts
    • O2 sensor switching speeds
  • Step 5: Combine with visual inspections and component tests
    If Mode 6 shows misfires on cylinder 3, for example, check that plug, coil, and injector physically.

🔗 Recommended Read: How to Check Engine Light with Scanner

Example: Diagnosing a Lazy Oxygen Sensor

On a Subaru Forester, I had rough acceleration and high fuel consumption. No codes were stored. Mode 1 live data showed slightly sluggish O2 sensor readings. Then I checked Mode 6—and saw the sensor consistently failed its voltage switching test.

Swapped the sensor—problem solved.

Mode 6 helped confirm the sensor wasn’t just slow—it was underperforming and ready to fail.

Pro Tips, Final Thoughts & FAQs – Mastering Mode 6 Like a Pro

By now, you should have a clear understanding of what is Mode 6 on a scan tool, how it works, and why it’s so valuable. But to truly get the most out of this hidden diagnostic mode, here are some practical tips I’ve learned through real-world experience.

Expert Tips for Using Mode 6 Effectively

✅ 1. Read Your Scan Tool’s Manual

It might sound boring, but most manuals include charts that explain Mode 6 TIDs, CIDs, and test descriptions. This can save you hours of confusion.

✅ 2. Use Online Test ID Resources

Forums like ScannerDanner, OBD-Codes.com, and vehicle-specific threads often include Mode 6 decoding charts by make/model.

✅ 3. Don’t Panic Over One-Time Fails

Not every failed test means a broken part. Mode 6 tests are sensitive, and minor failures may occur due to temporary conditions like cold starts or short trips.

✅ 4. Track Trends Over Time

If your scanner allows it, export Mode 6 results to a spreadsheet and compare them weekly. You’ll start seeing patterns and catch deteriorating parts early.

✅ 5. Pair Mode 6 with Live Data & DTCs

Use Mode 1 (live data) to verify if a failing sensor is slow to respond. Use Mode 3 to see if a code has finally appeared. Mode 6 should guide your diagnostics, not replace them entirely.

🔗 Related Article: How to Test Car Battery with a Multimeter

Why Every DIY Mechanic Should Know About Mode 6

Let’s be honest—most car issues don’t announce themselves with a blinking dashboard light. They sneak up quietly, through slight vibrations, rough idling, or subtle changes in fuel economy.

Mode 6 bridges that gap. It gives you the power to diagnose a component before it triggers a warning light, saving you time, money, and stress.

Here’s how it helped me:

  • Avoid unnecessary trips to the mechanic
  • Prevent breakdowns by catching parts before failure
  • Assist friends and family with pinpoint diagnostics
  • Build confidence in my own DIY repair skills

Final Thoughts: Is Mode 6 Worth Learning?

Absolutely. Learning how to use Mode 6 on a scan tool is like unlocking an advanced diagnostic level that most people overlook. Whether you’re a weekend DIYer or an aspiring automotive pro, Mode 6 will:

  • Make you a smarter mechanic
  • Reduce unnecessary parts swapping
  • Help you solve “invisible” car problems
  • Keep your vehicle in peak condition

So, the next time someone asks “what is Mode 6 on a scan tool?”, you’ll not only have the answer—you’ll have the advantage.

FAQs About Mode 6 on a Scan Tool

1. What is Mode 6 on a scan tool used for?

Mode 6 provides access to non-continuous monitor test results, allowing you to see diagnostic outcomes for components like oxygen sensors, catalytic converters, EGR systems, and more—even when no check engine light is present.

2. Can Mode 6 detect problems before a DTC is triggered?

Yes. That’s one of its biggest strengths. Mode 6 lets you identify parts that are near failure before they store a fault code or illuminate the MIL.

3. Is Mode 6 data easy to understand?

Not always. Basic scanners may show raw hexadecimal data, which can be confusing. Better scanners will translate Mode 6 into labeled test results. Use manuals and online resources to decode it if needed.

4. Do all OBD2 scanners support Mode 6?

No. Cheap code readers may not support it at all. Mid-range and professional-grade scan tools are your best bet for usable Mode 6 data.

5. What types of tests does Mode 6 include?

Typical Mode 6 tests include:

  • Catalyst efficiency
  • Oxygen sensor switching voltage
  • EGR system flow
  • EVAP leak detection
  • Cylinder misfire counts

6. Does Mode 6 vary by vehicle?

Yes. Each manufacturer decides how much Mode 6 data to report. Domestic vehicles like Ford and GM tend to report more detailed results than some imports.

7. Is it worth investing in a scanner with Mode 6 support?

If you’re serious about diagnosing your own vehicle, yes. The insight it offers can prevent costly repairs and unnecessary parts replacements.

Ready to dive deeper into advanced diagnostics?
Explore our full range of OBD2 scanner reviews and guides at BestOBD2Scanners.com.

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