Quick Answer
P0313 means your engine is experiencing misfires while running on low fuel. The most common fix is simply refueling your vehicle, but if misfires continue after filling the tank, you likely have a fuel quality issue, failing fuel pump, or ignition/fuel injection problem that needs diagnosis.
What Does P0313 Mean?
The P0313 diagnostic trouble code stands for “Misfire Detected With Low Fuel.” This code is triggered when your vehicle’s engine control unit (ECU) detects one or more cylinder misfires occurring simultaneously with a low fuel level condition. A misfire happens when one or more cylinders fail to produce proper combustion—meaning the air-fuel mixture either doesn’t ignite properly or burns incompletely.
The ECU monitors ignition timing, fuel injection, and combustion events in each cylinder. When it detects abnormal combustion patterns while the fuel tank is below a certain threshold, it sets this code. This is a protective measure because low fuel can cause fuel starvation issues that lead to misfires, but it also alerts you that something else may be wrong with the ignition or fuel system.
Common Symptoms
- Check Engine Light (CEL) is illuminated – This is typically the first sign
- Engine hesitation or stumbling – Particularly noticeable during acceleration
- Rough idle – Engine vibrates or feels unstable at stops
- Loss of power – Reduced acceleration and overall engine performance
- Fuel smell from exhaust – Unburned fuel exiting the tailpipe
- Engine knocking or pinging – Metallic sounds from the engine bay
- Difficulty starting – Engine cranks but takes longer to fire up
- Visible fuel gauge near empty – Tank level is critically low
Possible Causes
Listed from most to least common:
1. Low Fuel Level (Most Common)
The simplest and most frequent cause of P0313 is simply running on very low fuel. When fuel level drops below a certain point, the fuel pump may not maintain adequate pressure, causing fuel starvation in the injectors. This leads to lean-running cylinders that misfire. Adding fuel typically resolves this immediately.
2. Contaminated or Low-Quality Fuel
Fuel from a contaminated pump, old fuel, or fuel mixed with water can cause combustion problems. Poor fuel quality reduces octane rating and burn efficiency, making misfires more likely—especially when combined with low fuel levels. This is common after filling up at unfamiliar gas stations.
3. Failing Fuel Pump
A fuel pump nearing the end of its life may not maintain consistent pressure, particularly when the tank is low. The pump relies on fuel for cooling and lubrication, so low fuel accelerates pump wear. A weak pump cannot deliver adequate fuel volume to the injectors, causing lean misfires.
4. Clogged Fuel Filter
A severely restricted fuel filter reduces fuel flow to the injectors. When combined with low fuel level, the pressure drop becomes critical, and cylinders don’t receive enough fuel to ignite properly. Fuel filters typically need replacement every 15,000-30,000 miles.
5. Faulty Fuel Pressure Regulator
The fuel pressure regulator maintains consistent fuel system pressure. If it fails, pressure may drop too low, especially when the tank is low. This causes inadequate fuel delivery and misfires across multiple cylinders.
6. Spark Plug Issues
Worn, fouled, or gapped spark plugs may not fire reliably, particularly under the stress of lean fuel conditions. Spark plugs that are overdue for replacement (typically 30,000-100,000 miles depending on type) are more prone to misfiring.
7. Ignition Coil Failure
A failing ignition coil or coil pack cannot generate sufficient spark voltage. While this can cause misfires at any fuel level, it’s more pronounced when fuel is low and combustion conditions are already compromised.
8. Fuel Injector Problems
Clogged, leaking, or failing fuel injectors prevent proper fuel atomization and delivery. Multiple injector failures can cause misfires in several cylinders simultaneously, matching the pattern that triggers P0313.
9. Air Intake Leaks
Vacuum leaks or intake manifold leaks allow unmeasured air into the engine, creating an overly lean mixture. This is exacerbated by low fuel conditions and causes misfires as the ECU cannot compensate adequately.
10. Compression Issues
Low compression in one or more cylinders (from worn rings, valve problems, or head gasket leaks) prevents proper combustion. Low fuel levels compound this problem by reducing fuel pressure and ignition reliability.
Diagnostic Steps
Step 1: Fill the Fuel Tank
Your first action should always be to refuel completely. Drive the vehicle for 5-10 minutes to allow the ECU to re-evaluate conditions. If the check engine light clears and misfires stop, low fuel was the culprit. Use high-quality fuel from a reputable station.
Step 2: Check Fuel Quality
If misfires persist after refueling, the fuel may be contaminated. Consider draining the tank and refilling with premium fuel from a different station. Some shops can test fuel quality if contamination is suspected.
Step 3: Scan for Additional Codes
Use an OBD-II scanner to check for related codes such as:
- P0300 – Random/Multiple Cylinder Misfire
- P0301-P0308 – Individual Cylinder Misfire Codes
- P0087 – Fuel System Pressure Too Low
- P0089 – Fuel Pressure Regulator Control Circuit
These codes help narrow down the root cause.
Step 4: Inspect Spark Plugs
Remove and visually inspect all spark plugs. Look for:
- Excessive carbon buildup (black/sooty deposits)
- Electrode wear or erosion
- Incorrect gap spacing
- Oil fouling (wet, oily appearance)
Replace spark plugs if they appear worn or fouled. Use the correct type and gap specification for your vehicle.
Step 5: Test Fuel Pressure
Using a fuel pressure gauge, measure fuel system pressure:
- Connect the gauge to the fuel pressure test port (usually on the fuel rail)
- Turn the ignition on without starting the engine
- Record the pressure reading (typically 40-60 PSI depending on vehicle)
- Start the engine and note pressure under load
- Pressure should remain stable and within specification
Low or fluctuating pressure indicates a failing fuel pump, regulator, or clogged filter.
Step 6: Inspect Fuel Filter
Locate and visually inspect the fuel filter (usually under the vehicle or in the engine bay). If it appears dark, clogged, or hasn’t been replaced recently, replace it. This is an inexpensive maintenance item that can resolve fuel delivery issues.
Step 7: Check Ignition System
Test ignition coils and spark plug wires (if equipped) for proper resistance and voltage output. A multimeter can measure coil resistance; compare readings to manufacturer specifications. Failing coils should be replaced.
Step 8: Inspect for Vacuum Leaks
Listen for hissing sounds around the intake manifold, vacuum hoses, and PCV system while the engine idles. Spray brake cleaner around suspected leak areas; if RPM changes, you’ve found a leak. Repair or replace damaged hoses and gaskets.
Step 9: Check Fuel Injectors
Fuel injectors can be tested for proper spray pattern and electrical resistance. A professional fuel injector cleaning service or replacement may be necessary if injectors are clogged or failing.
Step 10: Perform a Compression Test
If all other diagnostics are normal, a compression test can reveal internal engine problems. Low compression in one or more cylinders indicates worn rings, valve issues, or head gasket failure—all of which require professional repair.
Repair Cost Estimates
Simple Fuel-Related Fixes:
- Refueling: $0 (free, just fill the tank)
- Fuel filter replacement: $50–$150
- Fuel system cleaning: $100–$300
Moderate Repairs:
- Spark plug replacement: $100–$300 (4-8 plugs)
- Ignition coil replacement: $150–$400 per coil
- Fuel pressure regulator: $200–$500
- Fuel injector cleaning/replacement: $300–$900
Major Repairs:
- Fuel pump replacement: $400–$1,200
- Engine compression repair (rings, valves, gaskets): $1,500–$5,000+
- Intake manifold gasket replacement: $300–$800
Note: Costs vary significantly by vehicle make/model, location, and whether you use OEM or aftermarket parts. Always get a diagnostic from a trusted mechanic before authorizing major repairs.
Can I Still Drive?
Severity: Moderate to High
Driving with P0313 is generally safe for short distances, but not recommended for extended periods:
- Short trips (under 10 miles): Generally safe. Refuel and monitor for improvement.
- Highway driving: Not recommended. Misfires reduce power and fuel economy, and could worsen engine damage.
- Extended driving: Avoid. Continuous misfiring can damage the catalytic converter, which is expensive to replace ($800–$2,500).
Safety Considerations:
- Misfires reduce engine power, affecting acceleration and hill-climbing ability
- Rough idle may make the vehicle unstable at traffic lights
- Unburned fuel in the exhaust can overheat and damage the catalytic converter
- In rare cases, severe misfires can cause engine damage if ignored
Recommended Action: Fill the fuel tank immediately and drive to a mechanic for diagnosis. If misfires continue after refueling, have the vehicle inspected within 24 hours to prevent further damage.