For 1990-2009 cars

### Circuit Description

DTC P0313 is designed to allow easy diagnosis of a misfire OR fuel trim DTC, which may have been due to a low fuel condition. If fuel pressure drops due to an inadequate fuel supply at the fuel pump, certain cylinders have run too lean setting a DTC P0171 or P0174. If the condition worsens, some cylinders may misfire setting DTCs P0300-P0306. DTC P0313 will set if a misfire or system too lean fuel trim DTC is set for a certain length of time when the fuel level in the fuel tank is below a certain level.

### Conditions for Setting the DTC

DTC P0313 will set when a misfire has been detected or the fuel trim limits have been exceeded, with the LTFT greater than 7.7 percent for idle/decel or greater than 24 percent for cruise/accel when:

• | The condition exists for longer than 30 seconds.

• | The fuel level is less than 11 L (2.9 gallons).

• | The engine speed between 520-6520 RPM.

• | The traction control is not active.

• | The intake air temperature (IAT ) is greater than -8°C (17°F).

• | The evaporative emission (EVAP) diagnostics are not running.

• | No misfire or fuel trim DTCs have been set before the fuel level went low.

• | No CKP or TP sensor DTCs have been set.

DTC P0313 diagnostic runs continuously once the above conditions have been met.

DTC P0313 is a type D DTC.

### Diagnostic Aids

Important:

• | If DTC P0300-P0306 are also set, check FUEL LEVEL in the scan tool DTC P0300-P0306 Failure Record to verify the misfire condition was due to low fuel level. If this is the case, fill the fuel tank above 11 L (2.9 gallons) and use the scan tool to monitor MISFIRE CURRENT CYL. 1-6 to verify no misfires exist. If misfires exist, refer to DTC P0300 or DTC P0301-P0306 diagnostics.

• | If DTC P0171 or P0174 is also set, check FUEL LEVEL in the scan tool DTC P0171 or P0174 Failure Record to verify the lean condition was due to low fuel level. If this is the case, fill the fuel tank above 11 L (2.9 gallons) and use the scan tool to monitor LT FT BN. 1-IDLE/DECEL. after the engine has been running for 2 minutes after the engine coolant temperature (ECT) has reached at least 80°C (176°F). If the percentages are above the ranges listed under DTC parameters, refer to DTC P0171 or P0174 diagnostics.

DTC P0313 should never set by itself.