DTC Advanced Diagnostics: P0300, P0301, P0302, P0303, P0304
DTC P0300: Random Misfire DetectedDTC P0301: No. 1 Cylinder Misfire DetectedDTC P0302: No. 2 Cylinder Misfire DetectedDTC P0303: No. 3 Cylinder Misfire DetectedDTC P0304: No. 4 Cylinder Misfire Detected
General Description
The crankshaft vibrates slightly when each cylinder fires. If a misfire occurs, the crankshaft rotation speed changes rapidly. The powertrain control module (PCM) monitors the crankshaft rotation speed based on the output pulses from the crankshaft position (CKP) sensor. By monitoring changes in the crankshaft rotation speed, the PCM counts the number of misfires and determines which cylinder is misfiring.
- P0300: If more than one DTC from P0301 through P0304 has been stored while misfires in multiple cylinders are detected, a malfunction is detected and a DTC is stored.
- P0301, P0302, P0303, P0304: If a misfire is detected, a DTC is stored.
There are two types of misfire detection:
- Type 1: When the number of misfires per 200 engine revolutions reaches the level that can damage the three way catalyst (TWC), a DTC is stored and the MIL blinks.
- Type 2: When the number of misfires per 1,000 engine revolutions reaches the level that affects FTP mode exhaust emissions but not severe enough to immediately damage the catalyst, a DTC is stored and the MIL comes on.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous | |
| Sequence | None | |
| Duration | Type 1 | Per 200 revolutions |
| Type 2 | Per 1,000 revolutions | |
| DTC Type | Two drive cycles, MIL on | |
Enable Conditions
| Condition | Minimum | Maximum | |
|---|---|---|---|
| Elapsed time after monitor finishing condition except immediate starting the engine | 1.0 second | - | |
| Engine coolant temperature [ECT Sensor 1] | None, unless the initial engine coolant temperature [ECT Sensor 1] is 14°F (-10°C) or less, in which case the monitor will not run until the engine coolant temperature [ECT Sensor 1] reaches 68°F (20°C) | ||
| Engine speed [Engine Speed]*1 | 500 rpm | 6,700 rpm | |
| Engine speed [Engine Speed]*2 | 500 rpm | 4,500 rpm | |
| MAP value [MAP Sensor (Hi Res)]* | 500 rpm** | 23.5 kPa (176.0 mmHg, 6.94 inHg) | - |
| 2,250 rpm** | 21.8 kPa (163.0 mmHg, 6.43 inHg) | - | |
| 500 rpm*** | 37.0 kPa (277.0 mmHg, 10.92 inHg) | - | |
| 2,750 rpm*** | 28.3 kPa (212.0 mmHg, 8.36 inHg) | - | |
| Fuel feedback | Other than during fuel cut-off operation | ||
| Other | Test-drive on a flat road to avoid misdetection | ||
*: Varies with driving conditions.
**: Rocker arm oil control solenoid: OFF
***: Rocker arm oil control solenoid: ON
*1: USA/Canada models
*2: Mexico models
[ ]: HDS Parameter
Malfunction Threshold
The number of misfires versus engine revolutions is equal to or greater than the values in the table.
| Misfire Type | The number of engine revolutions | The number of misfires |
|---|---|---|
| Misfire Type 1 (Severe) | Per 200 revolutions | 20*1 (17)*2 - 89 times**** |
| Misfire Type 2 (Light) | Per 1,000 revolutions | 28*1 (84)*2 times |
****: Depending on engine speed and load.
Possible Cause
The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- Ignition system failure
- Fuel supply system failure
- Intake air system failure
Confirmation Procedure
Operating Condition
- Start the engine. Hold the engine speed [Engine Speed] at 3,000 rpm without load (in P or N) until the radiator fan comes on.
- Drive the vehicle at a speed between 15 - 75 mph (25 - 120 km/h) for at least 3 minutes.
- Stop the vehicle, and let the engine idle for at least 3 minutes.
- When freeze data or the on-board snapshot is stored, drive the vehicle under those conditions instead of Driving Pattern step 2 or 3.
- When you have difficulty duplicating the DTC because of road conditions and traffic situations, repeat the driving pattern several times.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
Diagnosis Details
Conditions for setting the DTC
Misfire Type 1:
- If a type 1 misfire (catalyst damaging) occurs once, the MIL blinks once per second, a Pending DTC is stored, and the high rpm fuel injection stop system activates. The fuel injection stops, at high rpm only, on the cylinder that has the highest misfire counts. The MIL then continues to blink and the fuel injection stays off at high rpm, until the drive is completed.
- If a type 1 misfire occurs during a second drive cycle, the MIL and fuel injection behave the same and a Confirmed DTC is stored.
- After a type 1 misfire has been detected during two drive cycles, the MIL comes on and stays on beginning with the third drive cycle, unless the Pending DTC has been cleared by the PCM*****. Even if the MIL is on, it will start blinking if a type 1 misfire occurs.
- If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC, the freeze data, and the on-board snapshot are stored.
Misfire Type 2:
- If a type 2 misfire (emission-related but not severe enough to immediately damage the catalyst) occurs, a Pending DTC is stored, but the MIL does not come on or blink. If a type 2 misfire occurs during a second drive cycle, the MIL comes on and stays on unless the Pending DTC has been cleared by the PCM*****.
***** The Pending DTC is erased if either of these conditions is met:
- The vehicle is operated at least once under the same driving conditions as the first misfire detection, and no misfire is detected.
- 80 drive cycles, regardless of driving conditions, are completed with no misfire detected.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive drive cycles in which the engine conditions are similar to the first time the malfunction was detected. The MIL, the Pending DTC, the Confirmed DTC, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.