P0313 code definition
The code P0313 identifies a misfire code with low fuel level in the fuel tank. The code is often associated with diagnostic codes P0300, P0301, P0302, P0303, P0304, P0305, and P0306.
What the P0313 code means
P0313 is a generic OBD-II trouble code that is displayed in the powertrain control module (PCM). The code is an indication that the PCM has detected a misfire in one or more of the engine’s cylinders along with a low fuel reading in the fuel tank. The code is set in the PCM only after the engine has completed a minimum of six revolutions after starting, a misfire is detected, and the fuel level is down to the reserve portion of the fuel tank.
What causes the P0313 code?
- The fuel tank is low on fuel, and the fuel pump isn’t delivering enough fuel to run efficiently.
- One or more ignition coils are faulty, preventing ignition in their respective cylinders.
- Spark plugs are fouled and create little to no spark in their cylinder.
- An ignition cable has a cracked or rubbed insulator, generating weak spark or no spark to its spark plug.
- A fuel injector is failing or plugged so too much or too little fuel is injected into the cylinder.
- The engine control module is internally faulty.
Regardless of the cause of DTC P0313, the fuel level will be very low at the time the code is set.
What are the symptoms of the P0313 code?
When DTC P0313 is set in the ECM, the Check Engine light will be illuminated. It will remain on until the vehicle has passed at least three self-test cycles. Along with the Check Engine light, the engine may run rough when P0313 is present. Depending on the cause of the code, one or more cylinders may be running lean or misfiring, and there is potential for the engine to stall. Most commonly, the code illuminates because the fuel level is extremely low and the car is running out of fuel.
How does a mechanic diagnose the P0313 code?
DTC P0313 is diagnosed using an OBD-II scan tool. If the trouble code is stored or inactive, the mechanic may be able to clear the code. Once cleared, the vehicle should be road tested to verify the condition is gone, then codes checked again to ensure it isn’t once again pending or set.
If the code returns or there is a noticeable misfire, the first step is to fill the fuel tank. If the code is related to a low fuel level, this simple action can clear up the concern.
With a fuel tank filled above the minimum level, a mechanic will continue to diagnose the concern by checking connections to the affected cylinder. Typically, a misfire for a specific cylinder will be present as well. The mechanic can check that the ignition coil connector, fuel injector connector, and ignition cables are fully seated and locking tabs engaged where applicable. Wiring should be checked for corrosion and breaks as well as shorts to ground. If the condition is still present, the mechanic may begin to swap components on the system with another cylinder to determine which one is faulty. If the DTC follows a component to a different cylinder, they will know which part to replace.
Common mistakes when diagnosing the P0313 code
The most common mistake when diagnosing P0313 is neglecting to fill the fuel tank first. In many instances, the cause is because of poor fuel flow to the engine because of low fuel level. Otherwise, misdiagnosis can occur if parts are replaced before a thorough diagnosis is performed.
How serious is the P0313 code?
DTC P0313 can be a serious concern particularly if the engine is about to run out of fuel. You can be left stranded and require assistance or a tow to get to help. When the DTC is set for other reasons, it’s often less serious. A misfire can cause poor fuel consumption, higher emissions, and a rough-running engine, though usually it will continue to operate reliably.
What repairs can fix the P0313 code?
The common repairs for DTC P0313 are as such:
- Refuel the fuel tank. If the concern is due to low fuel level, symptoms will then disappear, then the DTC will simply need to be cleared.
- Replace an ignition coil or ignition cables. Once the particular component has been isolated, it can be replaced with a new one.
- Clean the fuel injectors. If the code is due to poor fuel injection, cleaning the injectors can clear up the condition. If they're broken, you can replace them.
- Replace the spark plugs. In some cases, fouled spark plugs in cold weather or worn spark plug electrodes can cause a misfire code.
Additional comments for consideration regarding the P0313 code
DTC P0313 is most commonly found on luxury vehicles such as BMW. On many other types of vehicles, you can run out of fuel without a Check Engine light illuminating or a misfire code setting in the PCM. On BMW vehicles, DTC P0313 can be likened to an early warning that you’re about to run out of fuel.
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