P0306
DTC P0306
DESCRIPTION
The engine control module (ECM) uses information from the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. A misfire rate that is high enough can cause 3-way catalytic converter damage. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for catalytic converter damage are preset. DTCs P0301-P0306 correspond to cylinders 1-6. If the ECM is able to determine that a specific cylinder is misfiring, the DTC for that cylinder sets.
CONDITIONS FOR RUNNING THE DTC
- DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, or P0338 are not set.
- The engine speed is between 400-7,000 RPM and steady.
- The delivered torque signal is more than 10 percent at idle with the transmission in neutral.
- The delivered torque signal is between 10-30 percent with the transmission in drive.
- The intake air temperature (IAT) is more than -30°C (-22°F).
- The engine run time is more than 45 seconds.
- The fuel level is more than 12 percent.
- The torque management is not active.
- The antilock brake/traction control (ABS/TC) system is not active.
- The ECM is not receiving a rough road signal.
- The fuel cut-off is not active, including the traction control, the deceleration, the high vehicle speed, and the high engine speed.
- DTC P0300 runs continuously when the above conditions exist for at least 1000 engine revolutions.
CONDITIONS FOR SETTING THE DTC
- The ECM detects a crankshaft rotation speed variation indicating a single cylinder misfire rate sufficient to cause emissions levels to exceed mandated standards.
- The condition exists for more than 4 seconds.
ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
DIAGNOSTIC AIDS
- A misfire DTC could be caused by an excessive vibration from sources other than the engine. Check for the following possible sources:
- Tire or wheel out of round or balance
- Variable thickness brake rotor or drum
- Drive shaft not balanced
- Certain rough road conditions
- Damaged accessory drive belt
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions
TEST
