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Mazda CX-9 Grand Touring. Manual - part 266



Turn the ignition switch to the ON
position (Engine off).



Inspect continuity between ignition
coil terminal C (wiring harness-side)
and body ground.



Is there continuity?

Yes

Repair or replace suspected part, then go to Step
10.

Go to the next step.

INSPECT PCM CONNECTOR FOR
POOR CONNECTION



Turn the ignition switch off.



Disconnect PCM connector.



Inspect for poor connection (such as
damaged/pulled-out pins, corrosion).



Is there any malfunction?

Yes

Repair or replace suspected part, then go to Step
10.

Go to the next step.

INSPECT IGNITION COIL SIGNAL
CIRCUIT FOR OPEN CIRCUIT



Inspect continuity between the
following circuits:



Ignition coil No.1 terminal C
(wiring harness-side) and PCM
terminal 2A (wiring harness-
side)



Ignition coil No.2 terminal C
(wiring harness-side) and PCM
terminal 2F (wiring harness-side)



Ignition coil No.3 terminal C
(wiring harness-side) and PCM
terminal 2K (wiring harness-
side)



Ignition coil No.4 terminal C
(wiring harness-side) and PCM
terminal 2W (wiring harness-
side)



Ignition coil No.5 terminal C
(wiring harness-side) and PCM
terminal 2AA (wiring harness-
side)



Ignition coil No.6 terminal C
(wiring harness-side) and PCM
terminal 2AE (wiring harness-
side)



Are there continuity?

Yes Go to the next step.

Repair or replace suspected part, then go to Step

10.

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 197

DTC P0420, P0430 [MZI-3.7]

DTC P0420, P0430 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES

INSPECT IGNITION COIL



Inspect ignition coil. (See IGNITION
COIL INSPECTION [MZI-3.7] .)



Are there ignition coil normal?

Yes Go to the next step.

Replace the ignition coil, then go to the next

step.

VERIFY TROUBLESHOOTING OF
DTC P0351, P0352, P0353, P0354, P0355
and P0356 COMPLETED



Verify that all disconnected connectors
reconnected.



Clear the DTC from the PCM memory
using the M-MDS.



Perform the "KOEO or KOER self-
test" using the M-MDS. (See
KOEO/KOER SELF TEST [MZI-
3.7].)



Is the PENDING CODE for the DTC
present?

Yes

Replace the PCM, then go to the next step. (See
PCM REMOVAL/INSTALLATION [MZI-
3.7] .)

Go to the next step.

VERIFY AFTER REPAIR PROCEDURE



Perform "AFTER REPAIR
PROCEDURE". (See AFTER
REPAIR PROCEDURE [MZI-3.7].)



Are any DTCs present?

Yes

Go to the applicable DTC inspection. (See DTC
TABLE [MZI-3.7].)

Troubleshooting completed.

DTC P0420

P0420: Catalyst system efficiency below threshold (RH)

DTC P0430

P0430: Catalyst system efficiency below threshold (LH)

DETECTION

CONDITION



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.

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 198

DIAGNOSTIC PROCEDURE

DTC P0420, P0430 (MZI-3.7) DIAGNOSTIC PROCEDURE

POSSIBLE

CAUSE



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.

STEP

INSPECTION

ACTION

VERIFY FREEZE FRAME DATA HAS
BEEN RECORDED



Has FREEZE FRAME DATA been
recorded?

Yes Go to the next step.

Record FREEZE FRAME DATA on the repair

order, then go to the next step.

VERIFY RELATED REPAIR
INFORMATION AVAILABILITY



Verify related Service Bulletins and/or
on-line repair information availability.



Is any related Service Bulletins
available?

Yes

Perform repair or diagnosis according to the
available Service Bulletins.



If the vehicle is not repaired, go to the
next step.

Go to the next step.

VERIFY RELATED PENDING CODE
OR STORED DTCs



Turn the ignition switch off then to the
ON position (Engine off).



Verify related pending code or stored
DTCs.



Is other DTCs present?

Yes

Go to the appropriate DTC troubleshooting. (See
DTC TABLE [MZI-3.7].)

Go to the next step.

INSPECT GAS LEAKAGE OF
EXHAUST SYSTEM



Visually inspect for exhaust gas
leakage in exhaust system.

Yes

Repair or replace malfunctioning exhaust parts,
then go to Step 7.

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

DTC P0442, P0456 [MZI-3.7]

DTC P0442, P0456 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES



Are there gas leakage?

INSPECT INSTALLATION OF FRONT
AND REAR HO2S



Inspect for looseness of front and rear
HO2Ss.



Are they it normal?

Yes Go to the next step.

Retighten sensor, then go to Step 7.

INSPECT TWC



Clear the DTC using the M-MDS.



Cycle the ignition switch off then back
to the ON position.



Inspect the TWC.



Is it normal?

Yes Go to the next step.

Replace the TWC, then go to the next step.

VERIFY TROUBLESHOOTING OF
DTC P0420, P0430 HAS BEEN
COMPLETED



Verify that all disconnected
connectors are reconnected.



Turn the ignition switch to the ON
position (Engine off).



Clear the DTC from the PCM memory
using the M-MDS.



Start the engine and run it at idle.



Retrieve DTCs using the M-MDS.



Is the PENDING CODE for this DTC
present?

Yes

Replace the PCM, then go to the next step. (See
PCM REMOVAL/INSTALLATION [MZI-
3.7] .)

Go to the next step.

VERIFY AFTER REPAIR
PROCEDURE



Perform the "AFTER REPAIR
PROCEDURE". (See AFTER
REPAIR PROCEDURE [MZI-3.7].)



Are any DTC present?

Yes

Go to the applicable DTC inspection. (See DTC
TABLE [MZI-3.7].)

Troubleshooting completed.

DTC P0442

P0442: Evaporative emission system leak detected (small leak)

DTC P0456

P0456: Evaporative emission system leak detected (very small leak)



P0442 indicates that a leak has been detected as small as 1 mm (0.04 in) in the

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 200

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