P1303

[P1203] or [P1303] The scan tool indicates Diagnostic Trouble Code (DTC) P1203 or P1303: Cylinder 3 misfire detected.

Description
Misfire detection is accomplished by monitoring the voltage of the spark plug with the spark plug voltage sensor which is built into the ignition coil.
If misfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and a misfire DTC will be stored. Then, after the misfire has ceased, the MIL will come on.
If misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and a misfire DTC 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.

P0171, P0172, P0174, P0175: Fuel supply system
P0401, P1491, P1498: EGR system
P1316, P1317, P1318, P1319: Spark Plug Voltage Detection System
P0335, P0336, P1336, P1337: CKP sensor
P1381, P1382, P1386, P1387: CYP sensor

Possible Cause
- Fuel injector clogging, fuel leakage, air leakage
- Fuel injector circuit open or shorted
- Injector resistor malfunction (A/T)
- Spark plug carbon deposits, fouling, malfunction
- Ignition coil malfunction
- ICM malfunction
- Ignition wires open
- Compression low
- Valve clearance out of specification

NOTE:
- If there is no freeze data of misfiring, just clear the DTC.
- If there is no freeze data of misfiring, test drives under various conditions are necessary.

NOTE:
- If there is no freeze data of misfiring, test drives under various conditions are necessary.