When you use an auto scan tool to check your vehicle’s health, you’ll likely encounter different types of diagnostic codes. Among these, “Pending Codes” can be a bit of a mystery. Understanding what pending codes mean is crucial for car owners and enthusiasts alike to effectively interpret diagnostic test results and maintain vehicle health.
This article will focus specifically on pending codes in car diagnostic tests. We’ll explain what pending codes are, how they differ from stored and permanent codes, and what steps you should take when you see a pending code appear on your scanner. Knowing the meaning behind these codes empowers you to address potential issues early and keep your car running smoothly.
Decoding Pending Codes: Your Car’s Early Warning System
Pending codes, also known as intermittent codes, are Diagnostic Trouble Codes (DTCs) that your vehicle’s On-Board Diagnostic (OBD-II) system has detected, but hasn’t yet confirmed as a persistent problem. Think of them as your car’s early warning system. They signal that something might be amiss, but the issue hasn’t occurred consistently enough to trigger the “Check Engine Light” or become a stored code.
Here’s a breakdown of the key characteristics of pending codes:
- Temporary and Tentative: Pending codes are temporary indicators. They suggest a potential fault, but the system needs more data to confirm it.
- Recent Issue Detection: These codes often appear after a recent event, like a slight sensor malfunction or a minor emission fluctuation. The system is saying, “I noticed something, but I’m not sure if it’s a real problem yet.”
- Awaiting Confirmation: The OBD-II system is designed to be thorough. It requires a fault to occur during multiple driving cycles or under specific conditions before upgrading a pending code to a stored code (and turning on the check engine light). This prevents false alarms from transient sensor blips.
- No Immediate Check Engine Light: Crucially, pending codes do not immediately illuminate the check engine light. This is because the issue is still under review by the system.
In essence, a pending code tells you: “There might be a problem, but it’s not critical yet. Keep an eye on it.”
Real-World Examples of Pending Codes
To better understand pending codes, let’s look at some common examples you might encounter when using a car diagnostic scanner:
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Oxygen Sensor Circuit Low Voltage (Pending P0131): Imagine an oxygen sensor, responsible for monitoring exhaust gases, sends a reading that’s slightly out of the normal range – perhaps a momentarily low voltage. This might trigger a pending code P0131. The system will then monitor the sensor’s performance over subsequent drives to see if the low voltage reading persists or was just a one-time occurrence.
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EVAP System Large Leak Detected (Pending P0455): The Evaporative Emission Control System (EVAP) prevents fuel vapors from escaping into the atmosphere. If your gas cap isn’t tightened properly after refueling, or there’s a minor temporary leak in the system, it might trigger a pending P0455 code. The system will then run tests during the next few drive cycles to check for a persistent leak.
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Mass Air Flow Sensor Circuit Range/Performance Problem (Pending P0101): The Mass Air Flow (MAF) sensor measures the amount of air entering the engine. If the sensor provides slightly inconsistent or fluctuating readings, perhaps due to a momentary obstruction or electrical glitch, it could generate a pending P0101 code. The system will continue to monitor the MAF sensor to determine if the readings stabilize or if a genuine issue exists.
These examples illustrate that pending codes often point to minor or intermittent issues that the OBD-II system is still evaluating. They are not necessarily urgent red flags, but they are definitely yellow flags signaling potential problems.
Pending Codes vs. Stored Codes vs. Permanent Codes: What’s the Difference?
It’s important to differentiate pending codes from other types of DTCs you’ll see on a scan tool: stored codes and permanent codes. Understanding their differences is key to proper car diagnostics.
Stored Codes (Confirmed Codes):
- Confirmed Problem: Stored codes represent confirmed, persistent issues. The OBD-II system has verified the fault over multiple drive cycles, meeting the criteria to declare it a definite problem.
- Check Engine Light ON: Stored codes are typically what trigger the Check Engine Light to illuminate on your dashboard, alerting you to a problem that needs attention.
- Action Required: Stored codes indicate that something is wrong and likely needs repair.
Permanent Codes (Non-Erasable Codes):
- Verified and Persistent: Permanent codes are similar to stored codes in that they indicate a confirmed fault. However, they are unique because they cannot be cleared using standard methods like a scan tool or battery disconnection.
- Emissions Focus: Permanent codes are specifically related to emissions system faults and are designed to ensure vehicles are properly repaired before passing emissions tests.
- Repair Mandate: Permanent codes remain until the underlying issue is resolved and the OBD-II system verifies the repair through specific drive cycles and tests. They are a strong indicator that a repair is necessary to ensure emissions compliance.
Here’s a table summarizing the key differences:
| Code Type | Meaning | Check Engine Light | Clearable with Scan Tool? | Urgency |
|---|---|---|---|---|
| Pending Codes | Potential issue, system still evaluating | No | Yes | Low to Medium |
| Stored Codes | Confirmed issue, needs attention | Yes | Yes | Medium to High |
| Permanent Codes | Confirmed issue, repair needed for clearing | Yes | No | High |
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What to Do When You See a Pending Code
Discovering a pending code during a car diagnostic test shouldn’t cause panic, but it shouldn’t be ignored either. Here’s a recommended course of action:
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Record the Code: Use your scan tool (like an ANCEL V6 Pro) to note down the exact pending code number and description. This information is crucial for further investigation.
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Research the Code: Use online resources, repair manuals, or consult a mechanic to understand what the pending code signifies. Knowing the potential issue associated with the code will help you prioritize and understand the next steps.
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Monitor the Situation: Since pending codes are intermittent, the best initial step is often to monitor your vehicle. Pay attention to your car’s performance, fuel economy, and any unusual noises or symptoms.
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Drive Normally: Continue driving your car as you normally would for a few days or a week. This allows the OBD-II system to gather more data and either confirm the fault (turning the pending code into a stored code and potentially illuminating the check engine light) or resolve the temporary issue.
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Re-scan: After a period of normal driving, re-scan your vehicle with your OBD-II scanner.
- Code Gone: If the pending code is gone, it’s possible the issue was transient and resolved itself. You can continue to monitor your vehicle, but no immediate action is needed.
- Code Persists (Still Pending): If the code is still pending, it indicates the issue is recurring. It’s wise to investigate further.
- Code Became Stored: If the pending code has become a stored code and the check engine light is now on, this confirms a persistent problem. It’s time to take action and diagnose and repair the underlying issue.
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Consider Professional Diagnosis: If the pending code persists, becomes a stored code, or if you’re unsure about how to proceed, it’s always a good idea to consult a qualified mechanic. They have the expertise and tools to accurately diagnose the problem and recommend the appropriate repairs.
Clearing Pending Codes:
While you can clear pending codes using an OBD-II scanner, it’s generally not recommended as the first step. Clearing the code simply hides the symptom without addressing the potential underlying issue. If you clear a pending code without fixing anything, the code (or a stored code) is likely to return if the problem persists.
Clearing codes is more appropriate after you’ve diagnosed and repaired a confirmed issue (stored code) to reset the system and verify the repair was successful.
Conclusion: Pending Codes are Your Car’s Whispers, Listen Closely
Pending codes are a valuable part of your vehicle’s diagnostic system. They are like whispers from your car, hinting at potential issues before they become major problems. Understanding “what does pending mean on a car diagnostic test” and knowing how to interpret these codes empowers you to be a proactive car owner.
By paying attention to pending codes, monitoring your vehicle’s health, and taking appropriate action when needed, you can ensure your car remains reliable, efficient, and on the road for longer. And for accurate and easy-to-understand diagnostic information, consider using a quality OBD-II scanner from ANCEL, like their range of bluetooth OBD2 readers and professional scan tools.
FAQs About Pending Codes
Can I ignore a pending code?
While pending codes don’t signal an immediate crisis, ignoring them is not advisable. They indicate a potential issue that could worsen over time. It’s best to monitor the code and investigate if it persists or becomes a stored code.
Will a pending code prevent my car from passing an emissions test?
Generally, pending codes alone will not cause you to fail an emissions test. However, in some jurisdictions, a large number of pending codes or specific types of pending codes might raise concerns during inspection. It’s always best to address any pending codes before an emissions test to ensure your vehicle is in top condition.
How many drive cycles does it take for a pending code to become stored?
The number of drive cycles required for a pending code to become stored varies depending on the specific code and vehicle manufacturer. It typically takes between one to three drive cycles where the fault condition is detected.
Should I take my car to a mechanic immediately if I see a pending code?
Not necessarily. For a pending code, monitoring the situation and researching the code is a good first step. If the code persists, becomes a stored code, or if you notice any drivability issues, then consulting a mechanic is recommended.
Can clearing a pending code cause problems?
Clearing a pending code itself doesn’t directly cause problems. However, if you clear a code without addressing the underlying issue, the problem is likely to return, and you might miss an opportunity to address a minor issue before it becomes more serious and potentially more expensive to repair.
