P0300

The scan tool indicates Diagnostic Trouble Code (DTC) P0300*3, P1300*4 and some of P1201 -P1206 or P1301-P1306: Random misfire.




Troubleshooting
By test-driving, determine the conditions during which misfire occurs. Depending on these conditions, test in the order described in the table.

NOTE: If misfire doesn't recur, some possible causes are fuel that doesn't meet owners manual spec, lack of fuel, carbon deposits on spark plug, etc.

Description
Misfire detection is accomplished by monitoring the voltage of the spark plug with the spark plug voltage sensor which is built in to the ignition coil.
If misfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and DTC P1300*3 or P0300*4, some of DTCs P1201 through P1206 or some of DTCs P1301 through P1306 will be stored. Then, after misfire has ceased, the MIL will come on and stay on whenever the ignition switch is ON (II).
If misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and DTC P1300*3 or P0300*4, some of DTCs P1201 through P1206 or some of DTCs P1301 through P1306 will be stored.

NOTE: If some of the DTCs listed below are stored at the same time as a misfire DTC, troubleshoot those DTCs first, then troubleshoot the misfire DTC.

P0106*1, P1128*2, P1129*2: MAP sensor
P0171, P0172, P0174, P0175: Fuel metering
P0401, P1491, P1498: EGR system
P0335, P0336, P1336, P1337, P1381, P1382, P1386, P1387: CKP/CYP sensor
P0505: Idle Control System
P1508: IAC valve

*1: '96 model only
*2: '97 - 03 models
*3: '96-97 models
*4: '98 - 00 models

Possible Cause
- Fuel pump insufficient fuel pressure, amount of flow
- Fuel line clogging, blockage, leakage
- Fuel filter clogging
- Fuel pressure regulator stuck open
- EGR system malfunction
- Ignition coil wire open, leakage
- Ignition control module malfunction
- MAP sensor range/performance, poor response*1
- IAC valve malfunction
- Fast idle thermo valve malfunction
- Carbon deposits on valves
- Compression low
- Gasoline does not meet Owner's Manual spec., lack of fuel