Toyota Celica 2005 Repair Manual page 658

DTC P0300
DTC P0301
DTC P0302
DTC P0303
DTC P0304
CIRCUIT DESCRIPTION
When a misfire occurs in the engine, hydrocarbons (HC) are output in high concentrations. If this HC con-
centration is high enough, there could be an increase in exhaust emission levels. High concentrations of HC
passing through the catalyst also cause the temperature of the catalyst to increase, possibly damaging the
catalyst. To prevent this increase in the emissions and limit the possibility of thermal damage, the ECM moni-
tors the misfire rate. When the temperature of the catalyst reaches a point of thermal degradation, the ECM
will blink the MIL. For monitoring misfire, the ECM uses both camshaft position sensor and the crankshaft
position sensor. The camshaft position sensor is used to identify misfiring cylinders and crankshaft position
sensor is used to measure variations in the crankshaft rotation speed. A misfire is counted when crankshaft
rotation speed variations exceed threshold values.
The ECM illuminates the MIL if the misfiring rate exceeds a threshold value, which could cause emission
deterioration.
DTC No.
P0300 Misfiring of random cylinder is detected
P0301
P0302
Misfiring of each cylinder is detected
P0303
P0304
HINT:
When codes for a misfiring cylinder are recorded repeatedly but no random misfire code is recorded, it indi-
cates that the misfires have been detected and recorded at different times.
2005 CELICA (RM1131U)
DIAGNOSTICS
Random/Multiple Cylinder Misfire Detected
Cylinder 1 Misfire Detected
Cylinder 2 Misfire Detected
Cylinder 3 Misfire Detected
Cylinder 4 Misfire Detected
DTC Detection Condition
− ENGINE (2ZZ−GE)
S Open or short in engine wire
S Connector connection
S Vacuum hose connection
S Ignition system
S Injector
S Fuel pressure
S Mass air flow meter
S Engine coolant temperature sensor
S Compression pressure
S Valve clearance
S Valve timing
S VVTL−i system (rocker arm)
S PCV hose connection
S PCV hose
S ECM
657
Trouble Area
DI−459
DIC7F−02