Misfire Detected with Low Fuel
Your engine is misfiring (cylinders not firing properly) while the fuel tank is low, like trying to run a relay race when the baton keeps dropping and you're running on fumes. The ECU detected this combination and lit up the check engine light because both conditions together can damage your catalytic converter.
The ECU monitors fuel tank level via the fuel sender and simultaneously tracks combustion events in each cylinder using crankshaft speed variation and oxygen sensor readings. When fuel level drops below a threshold while misfire counts exceed limits, the code triggers to prevent catalytic converter damage from unburned fuel.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Fuel Tank Level | Above 15-25% capacity | Below 15-25% with active misfires |
| Misfire Count | Less than 1-2% per 1000 revolutions | Above 2% misfires detected |
Code P0313 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0313 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.