Mazda CX-9 Grand Touring 2007 Manual page 558

2007 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.5) - CX-9
DTC P0420, P0430 (MZI-3.5) DETECTION CONDITION AND POSSIBLE CAUSES
DTC P0420 P0420: Catalyst system efficiency below threshold (RH)
DTC P0430 P0430: Catalyst system efficiency below threshold (LH)
DETECTION
CONDITION
POSSIBLE CAUSE
DIAGNOSTIC PROCEDURE
DTC P0420, P0430 (MZI-3.5) DIAGNOSTIC PROCEDURE
STEP
1 VERIFY FREEZE FRAME DATA
HAS BEEN RECORDED
Has FREEZE FRAME DATA
been recorded?
2 VERIFY RELATED REPAIR
INFORMATION AVAILABILITY
Verify related Service Bulletins
2007 Mazda CX-9 Grand Touring
P0420 indicates right bank catalyst system efficiency is below the acceptable
threshold.
P0430 indicates left bank catalyst system efficiency is below the acceptable
threshold.
Use of leaded fuel.
Oil contamination
Cylinder misfiring.
Damaged HO2S.
Malfunctioning CHT sensor.
Downstream HO2S wires improperly connected.
Fuel pressure too high.
Damaged exhaust system pipe.
Damaged exhaust manifold.
Damaged muffler/tailpipe ass
NOTE:
Internal deterioration of a catalytic converter is usually caused by
abnormal engine operation front of the catalyst. Events that can
produce higher than normal temperatures in the catalyst are
particularly suspect, such as misfiring. Incorrect HO2S signal
input (e.g., rich/lean signal when engine is operating under
rich/lean conditions) can cause an abnormal temperature increase
in the catalyst. CHT sensor DTCs can indicate that the thermostat
is not operating correctly or that the engine coolant level is not
filled to specification, producing above normal operating
temperatures.
INSPECTION ACTION
Yes Go to the next step.
No Record FREEZE FRAME DATA on the
repair order, then go to the next step.
Yes Perform repair or diagnosis according to
the available Service Bulletins.
If the vehicle is not repaired, go to