DIAGNOSTIC PROCEDURE
DTC P0420, P0430 (MZI-3.7) DIAGNOSTIC PROCEDURE
POSSIBLE
CAUSE
z
Damaged exhaust system pipe.
z
Damaged exhaust manifold.
z
Damaged muffler/tailpipe ass
NOTE:
z
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.
STEP
INSPECTION
ACTION
1
VERIFY FREEZE FRAME DATA HAS
BEEN RECORDED
z
Has FREEZE FRAME DATA been
recorded?
Yes Go to the next step.
No
Record FREEZE FRAME DATA on the repair
order, then go to the next step.
2
VERIFY RELATED REPAIR
INFORMATION AVAILABILITY
z
Verify related Service Bulletins and/or
on-line repair information availability.
z
Is any related Service Bulletins
available?
Yes
Perform repair or diagnosis according to the
available Service Bulletins.
z
If the vehicle is not repaired, go to the
next step.
No
Go to the next step.
3
VERIFY RELATED PENDING CODE
OR STORED DTCs
z
Turn the ignition switch off then to the
ON position (Engine off).
z
Verify related pending code or stored
DTCs.
z
Is other DTCs present?
Yes
Go to the appropriate DTC troubleshooting. (See
DTC TABLE [MZI-3.7]
.)
No
Go to the next step.
4
INSPECT GAS LEAKAGE OF
EXHAUST SYSTEM
z
Visually inspect for exhaust gas
leakage in exhaust system.
Yes
Repair or replace malfunctioning exhaust parts,
then go to Step 7.
No
Go to the next step.
2008 Mazda CX-9 Grand Touring
2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9
Microsoft
Sunday, November 15, 2009 10:08:37 AM
Page 199
© 2005 Mitchell Repair Information Company, LLC.