Toyota Celica 2005 Repair Manual page 360

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
can also cause the temperature of the catalyst to increase, possibly damaging the catalyst. To prevent in-
creases in emissions and limit the possibility of thermal damage, the ECM monitors the misfire rate. When
the temperature of the catalyst reaches a point of thermal degradation, the ECM will blink the MIL. For moni-
toring a misfire, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The
camshaft position sensor is used to identify misfiring cylinders and the 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.
If the misfiring rate exceeds the threshold value and could cause emissions deterioration, the ECM illumi-
nates the MIL.
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 (1ZZ−FE)
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 sensor
S Engine coolant temperature sensor
S Compression pressure
S Valve clearance
S Valve timing
S PCV hose connection
S PCV hose
S ECM
359
Trouble Area
DI−161
DIC6T−02