Mazda CX-9 Grand Touring 2009 Manual page 1015

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9
REPAIR PROCEDURE [MZI-
3.7].)
Are any DTC present?
DTC P0300 [MZI-3.7]
DTC P0300 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES
DTC P0300 Random misfire detected
The PCM monitors the crankshaft position sensor input signal interval time. The
PCM calculates the change of the interval time for each cylinder. If the change of
interval time exceeds the pre-programmed criteria, the PCM detects a misfire in
the corresponding cylinder. When the engine is running, the PCM counts the
DETECTION
number of misfires that occurred at 200 crankshaft revolutions and 1,000
CONDITION
crankshaft revolutions and calculates the misfire ratio for each crankshaft
revolution. If the ratio exceeds the pre-programmed criteria, the PCM determines
that a misfire, which can damage the catalytic converter or affect emission
performance, has occurred.
CMP sensor malfunction
CKP sensor malfunction
Ignition coil malfunction
Ignition system malfunction
MAF sensor contamination
Excess air suction in intake air system (between MAF/IAT sensor and dynamic
chamber)
Vacuum hoses damages or improper connection
Fuel pump malfunction
Fuel pressure regulator malfunction
POSSIBLE
Fuel line clogged
CAUSE
Fuel filter clogged
Fuel runout
Poor quality fuel
Fuel leakage in fuel line
Insufficient compression
Variable valve timing control system improper operation
Purge solenoid valve malfunction
PCV valve malfunction
Related connector and terminal malfunction
Related wiring harness malfunction
DIAGNOSTIC PROCEDURE
2008 Mazda CX-9 Grand Touring
No Troubleshooting completed.