What Is a Pending Fault Code? | Explained

A pending code is easy to misread. It often carries the same five-character number as a confirmed code, and it can appear on a scanner while the dashboard shows nothing wrong. That does not mean the car has decided the fault is real. It means the car is still deciding.

What you do next depends on whether the fault repeats, whether symptoms are present, and whether the monitor has run again.

What a pending fault code actually means

A pending fault code, also called a pending diagnostic trouble code (DTC), is recorded when a self-test, or monitor, detects a reading outside its expected range during one trip. The computer stores that first failure while it waits for more evidence.

Think of it as a first observation rather than a verdict. A sensor can spike briefly or a misfire can happen once, so the system holds the fault in pending status until the pattern is clearer.

This is why a pending code does not, by itself, tell you which part has failed. It points to a system and a condition, such as a lean mixture or a misfire. The cause still needs checking.

How a pending code is created

OBD2 systems run regular checks on misfire detection, fuel trim, oxygen sensors, catalyst efficiency, and the evaporative system. Each monitor needs certain conditions, such as engine temperature, speed, or load, before it can run.

When those conditions are met and the test runs, the computer compares the result with its limits. If the result fails, it records a pending code. For many two-trip faults, that first failure is not yet enough to turn on the malfunction indicator lamp, commonly called the check engine light.

On the next trip, the system watches again. The second trip usually needs to be similar enough for the same monitor to run and fail under comparable conditions. A short drive may not count if the monitor never runs.

Pending, confirmed, and permanent codes compared

Pending is the earliest stage. Confirmed, often called stored, means the fault has met the confirmation rule. Permanent is a stricter record for some confirmed emissions faults, and it clears only after the vehicle itself runs the related test and passes it.

The table is a guide, because makers set different trip rules. For full detail, see stored vs pending trouble codes and what a permanent OBD2 code is.

Why the check engine light usually stays off

For most two-trip faults, the light is deliberately delayed until a second failure confirms a verified emissions problem. A clean dashboard therefore does not prove the car found nothing.

Exceptions exist. Some one-trip faults, sometimes called Type A faults, can turn the light on immediately. A severe misfire that risks catalyst damage may make the light flash, which is a prompt to reduce driving and get the car checked promptly.

The light can also already be on for a different, confirmed fault while a new pending code sits in the background. Read each status separately. This early warning is also why a scan can find a problem before the light appears, as explained in whether an OBD2 scan can find a problem before the check engine light comes on.

What happens next: three possible outcomes

Once a pending code is set, it normally follows one of three paths, depending on whether the monitor runs again and whether the fault repeats.

1. It becomes confirmed. The same fault is detected again on a subsequent, similar trip. The code moves to confirmed status and the light usually turns on.
2. It clears on its own. The monitor runs again and passes, or the fault does not repeat over the required number of successful cycles. The pending code is then erased without ever turning the light on.
3. It stays pending. The monitor has not run again under the right conditions, so the system has neither confirmed nor cleared the fault.

A pending code that stays for weeks does not automatically mean the fault is getting worse. It may simply mean the car has not had the right kind of drive to complete that monitor. A code that disappears proves only that the fault did not repeat when the monitor last ran.

How to find a pending code on a scanner

Not every scanner shows pending codes in the same place. Some list them under a separate Pending section, some mark them with PD or Pending next to the code, and some show them only in a specific menu. A basic reader that reports only confirmed codes can show zero codes while a pending code is present.

Pending codes are commonly accessed through Mode 07, while confirmed codes use Mode 03. That explains why two tools can differ: one may read only the confirmed list. For the confirmed-code side, see what OBD2 Mode 03 is.

When you scan, write down the code number, its status, and any symptoms or recent changes, such as a loose fuel cap or recent work on the car. That note makes the next scan useful.

If your scanner shows no status label, check its manual for a pending, stored, or permanent filter. Do not assume an unlabelled code is confirmed. One reader manual explains that for a Type B fault, a pending code is set on the first trip without the light, and if it recurs on the second trip, the light illuminates and the code is stored, as described in the Innova 3020b OBD2 code reader manual.

What to do when you see a pending code

Start with symptoms, not the code alone. If the engine is misfiring badly, overheating, stalling, or the light is flashing, get the car checked promptly. If driving feels normal and the light is off, a calm, ordered check is usually right.

1. Record it. Note the code, its pending status, the date, and the driving conditions.
2. Check the simple things first. Look for a loose or damaged fuel cap if the code relates to the evaporative system, and check for obvious loose connectors or damaged hoses. Do not start replacing sensors at this stage.
3. Drive normally for a few varied trips. Include warm-up and steady driving where safe and legal, so the monitor has a chance to run again.
4. Rescan and compare. If the code is gone, note that it cleared without confirmation. If it is now confirmed, you have a verified fault to diagnose. If it is still pending, the monitor may not have run, or the fault may be intermittent.
5. Diagnose the confirmed fault, not the pending label. Once confirmed, use live data and system checks for that code. A pending code is a lead; a confirmed code is the starting point for proper diagnosis.

Clearing a pending code early removes the evidence you need and resets readiness monitors. See how long a cleared code stays gone for why a cleared code can return quickly if the fault is still present.

Pending codes, emissions tests, and buying a car

A pending code alone usually does not turn the check engine light on, and a test that checks for an illuminated light and confirmed faults will often pass with only a pending code present. That is not a guarantee in every state or test type, so check the rules where the car will be tested.

When buying a used car, a pending code is not proof of a fault, yet it is evidence that a monitor failed once recently. Ask whether it has repeated, whether codes were cleared recently, and whether readiness monitors are complete.

Frequently Asked Questions

Does a pending code mean the check engine light will come on?

Not necessarily. For most two-trip faults, the light comes on only if the same fault is detected again on a second, similar trip. If it does not repeat, the pending code can clear without the light ever turning on. One-trip faults are the exception.

Can I keep driving with a pending code?

Usually yes, if driving feels normal, the light is off, and there are no severe symptoms such as heavy misfiring, overheating, stalling, or a flashing light. A pending code is a reason to watch and rescan. If symptoms are severe, get the car checked promptly.

How long does it take for a pending code to clear or become confirmed?

There is no fixed number of days. It depends on whether the relevant monitor runs again and whether the fault repeats. That can happen over a few varied trips, or take longer if the monitor needs specific conditions.

Will a pending code fail an emissions test?

A pending code alone usually does not fail a test that looks for an illuminated light and confirmed faults, because the fault has not been confirmed. Rules vary by location and test type, and a pending code can become confirmed before the test if the fault repeats.

Should I clear a pending code?

Usually no, at least not before you record it and rescan. Clearing removes the early evidence and resets monitors, making it harder to tell whether the fault is repeating. Clear a code after diagnosis and repair, rather than to make the scanner screen look clean.

Why does one scanner show a pending code while another shows no codes?

Many basic readers show only confirmed codes by default, while other tools also check the pending list. Menus, labels, and modes also differ. Check for a separate pending section or Mode 07 view before concluding that the car found nothing.

Conclusion

A pending fault code is best read as a question, not an answer. It tells you a monitor failed once and is waiting to see whether that failure repeats. Record the code and its status, check for symptoms and simple causes, drive normally so the monitor can run again, and rescan. If it clears, you have avoided an unnecessary repair. If it confirms, you have a verified fault to diagnose.