Understanding car diagnostic codes can be confusing, especially when you’re faced with terms like “Current Pass” on your car scanner. This term is crucial for interpreting your vehicle’s health, particularly when dealing with the check engine light and preparing for emission tests. Let’s break down what “Current Pass” means and how it fits into the broader picture of car diagnostics.
When you connect a car scanner to your vehicle’s OBD-II port, it retrieves a wealth of information about your car’s systems. One important aspect is the status of various diagnostic tests. These tests are run by your car’s computer (ECU/PCM) to monitor different components and systems, primarily related to emissions control. “Current Pass” is a status indicator for these tests.
What Does “Current Pass” Really Mean?
Simply put, “Current Pass” on a car scanner signifies that a specific diagnostic test has been completed in the current drive cycle and the system or component being tested has passed. It means that at the time of the scan, no fault was detected for that particular test. This is generally good news and indicates that the system is functioning as expected, at least for that specific parameter being monitored.
However, it’s important to understand the context. “Current Pass” doesn’t guarantee that everything is perfect forever. It’s a snapshot in time. Here’s why:
- Tests Run During Drive Cycles: Many diagnostic tests, especially those related to emissions, are not continuously running. They are performed during specific “drive cycles.” A drive cycle is a set of driving conditions (like cold start, idling, cruising at different speeds, deceleration, etc.) that the car needs to experience for certain tests to run. If a test hasn’t run in the current drive cycle, it might not show “Current Pass” yet, even if the system is actually fine.
- Intermittent Issues: Some car problems are intermittent. A sensor might malfunction only under certain conditions. If the scanner reads “Current Pass,” it only means the system passed the test when it was run. The issue could still reappear later.
- Different Code Statuses: “Current Pass” is just one of several possible statuses you might see on a car scanner. To get a complete picture, it’s essential to understand how it relates to other statuses like “Current Fail,” “Pending Codes,” “Permanent Codes,” and “Cleared Codes.”
Understanding Different Code Statuses
To fully grasp the meaning of “Current Pass,” let’s differentiate it from other common code statuses:
Current Codes vs. History Codes
Car scanners typically distinguish between “Current Codes” and “History Codes” (or sometimes “Stored Codes”).
- Current Codes: These are fault codes that are actively present when the scan is performed. If a system is failing right now, it will likely trigger a “Current Code.” However, a “Current Pass” status implies no “Current Codes” are active for the tested system.
- History Codes: These are codes that were present in the past but are not currently active. They are stored in the ECU’s memory. “Current Pass” doesn’t directly relate to history codes but knowing history codes exist helps understand that past issues might have been resolved.
“Current Pass” vs. “Pending” vs. “Permanent” Codes
Within the “Current” status, you might see “Pass” or “Fail.” Additionally, you’ll encounter “Pending” and “Permanent” codes:
- Pending Codes: These are also known as “maturing codes.” They indicate that the ECU has detected a potential issue, but it needs to be verified over multiple drive cycles before a “Current Code” (and potentially a check engine light) is triggered. If a test shows “Current Pass,” there are no pending codes for that test at the moment.
- Permanent Codes: Introduced with more stringent emission regulations, permanent codes are fault codes that cannot be cleared by simply disconnecting the battery or using a generic code reader. They can only be cleared by the ECU itself after the underlying problem has been fixed and the system passes the diagnostic test over multiple drive cycles. A “Current Pass” status is essential for clearing permanent codes related to the passed test.
- “Cleared Codes”: When you manually clear codes with a scanner, you are typically clearing “Current” and “Pending” codes. However, permanent codes remain until the issue is resolved and the system passes its self-tests.
Drive Cycles and “Current Pass” for Emission Readiness
The concept of “Current Pass” is particularly important when preparing for vehicle emission tests (smog checks). For a vehicle to pass an emission test, certain emission-related systems need to have run their diagnostic tests and passed. These are often referred to as “Readiness Monitors” or “OBD Monitors.”
Common readiness monitors include:
- Catalytic Converter Monitor
- Oxygen Sensor Monitor
- Evaporative System (EVAP) Monitor
- EGR System Monitor
- Secondary Air System Monitor
- Fuel System Monitor
For each of these monitors, a car scanner will typically show a status: “Ready” or “Not Ready.” For a monitor to be “Ready,” it usually means the diagnostic test associated with it has run and achieved a “Current Pass” status during a drive cycle.
In many regions, for a vehicle to pass an emission test, most (but not necessarily all) of these monitors need to be in a “Ready” state. If monitors are “Not Ready,” it often means the required drive cycles haven’t been completed since the last time codes were cleared, or there might be an underlying issue preventing the test from running and passing.
Troubleshooting Based on “Current Pass” and Other Statuses
- Seeing “Current Pass” for all or most monitors? That’s generally good! It suggests your car’s emission systems are currently functioning within acceptable parameters. If your check engine light is off and emission monitors are “Ready” (showing “Current Pass”), you are likely in good shape for an emission test.
- Seeing “Current Fail” or “Not Ready” for some monitors? This indicates a potential issue. You should investigate further. Check for specific fault codes related to the failing or not ready monitors. Address any underlying mechanical or electrical problems. After repairs, you may need to perform a drive cycle to allow the monitors to run their tests and hopefully achieve “Current Pass” status.
- Recently cleared codes and monitors are “Not Ready”? This is normal immediately after clearing codes. You need to perform a proper drive cycle as specified by your vehicle’s manufacturer to allow the monitors to run their tests. Keep monitoring the status after drive cycles. If they don’t become “Ready” (achieve “Current Pass”), there might be a persistent issue.
Conclusion
“Current Pass” on a car scanner is a positive indicator, showing that a specific diagnostic test has been completed and passed in the current drive cycle. It’s a crucial piece of information for understanding your vehicle’s health, especially concerning emission systems and readiness for smog checks. However, it’s just one piece of the puzzle. To get a comprehensive understanding, you need to consider “Current Pass” in conjunction with other code statuses, readiness monitors, and any underlying symptoms your car might be exhibiting. Always consult your vehicle’s repair manual or a qualified mechanic for in-depth diagnosis and repair of any detected issues.
