Mazda CX-9 Grand Touring. Manual - part 278

DTC P050E [MZI-3.7] 

DTC P050E (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

4



Remove air cleaner element with the 
engine running.  



Is the engine speed increased?  

Yes 7.

No

Go to the next step.

5

INSPECT INTAKE AIR SYSTEM FOR 
EXCESSIVE AIR SUCTION  



Visually inspect the hose in intake air 
system for looseness or damages.  



Is there any malfunction?  

Yes

Repair or replace the malfunctioning part, then 
go to Step 7.

No

Go to the next step.

6

INSPECT THROTTLE BODY 
PASSAGE  



Is the throttle body clogged?  

Yes

Clean or replace the throttle body passage, then 
go to Step 7.

No

Go to the next step.

7

VERIFY TROUBLESHOOTING OF 
DTC P0507 HAS BEEN COMPLETED  



Verify that all disconnected 
connectors reconnected.  



Start the engine.  



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



Depress brake pedal for 14 s or more. 



Is PENDING CODE for this DTC 
present?  

Yes

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

No

Go to the next step.

8

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].)

No

Troubleshooting completed.

DTC P050E

Cold start engine exhaust temperature out of range

DETECTION 

CONDITION 



The PCM calculates the actual catalyst warm up temperature during a cold start. 
The PCM then compares the actual temperature to the expected catalyst 
temperature model. The difference between the actual and expected temperatures 
is a ratio. When this ratio exceeds the calibrated value this DTC is set and the 
malfunction indicator lamp (MIL) illuminates.  



Intake air restriction  

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:38 AM

Page 245 

© 2005 Mitchell Repair Information Company, LLC. 

DIAGNOSTIC PROCEDURE 

DTC P050E (MZI-3.7) DIAGNOSTIC PROCEDURE 

POSSIBLE 

CAUSE 



Exhaust restriction  



Mechanical concern with the engine  



Throttle body malfunction  



Vacuum leakage  



PCM malfunction  

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS 
BEEN RECORDED  



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  



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.  

No

Go to the next step.

3

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].)

No

Go to the next step.

4

INSPECT AIR CLEANER ELEMENT  



Remove air cleaner element with the 
engine running.  



Is the engine speed increased?  

Yes

Replace the air cleaner element, then go to Step 
9.

No

Go to the next step.

5

INSPECT INTAKE AIR SYSTEM FOR 
EXCESSIVE AIR SUCTION  



Visually inspect the hose in intake air 
system for looseness or damages.  



Is there any malfunction?  

Yes

Repair or replace the malfunctioning part, then 
go to Step 9.

No

Go to the next step.

INSPECT THROTTLE BODY 
PASSAGE  

Yes

Clean or replace the throttle body passage, then 
go to Step 9.

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:38 AM

Page 246 

© 2005 Mitchell Repair Information Company, LLC. 

DTC P053A [MZI-3.7] 

DTC P053A (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

6



Is the throttle body clogged?  

No

Go to the next step.

7

INSPECT ENGINE COMPRESSION  



Inspect the engine compression. (See 
COMPRESSION INSPECTION 
[MZI-3.7] .)  



Is the engine compression normal?  

Yes Go to the next step.

No

Overhaul the engine, then go to Step 9.

8

INSPECT FOR RESTRICTION IN 
EXHAUST SYSTEM AND TWC  



Is there any restriction?  

Yes

Replace malfunctioning part, then go to the next 
step.

No

Go to the next step.

9

VERIFY TROUBLESHOOTING OF 
DTC P050E 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.  



Perform the "KOEO and KOER self-
test". (See KOEO/KOER SELF 
TEST [MZI-3.7].)  



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] .)

No

Go to the next step.

10

VERIFY AFTER REPAIR 
PROCEDURE  



Perform the "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].)

No

Troubleshooting completed.

DTC P053A

PCV valve heater control circuit/open

DETECTION 

CONDITION 



This DTC is set when the PCM detects a PCV valve heater circuit 
malfunction.  



Open circuit between PCV valve heater control terminal A and main relay 
No.1  

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:38 AM

Page 247 

© 2005 Mitchell Repair Information Company, LLC. 

POSSIBLE CAUSE 



Open circuit between PCV valve heater fitting terminal A and main relay 
No.1  



Short to ground circuit between PCV valve heater control terminal B and 
PCM terminal 2BL  



Short to ground circuit between PCV valve heater fitting terminal B and PCM
terminal 2AU  



Short to power circuit between PCV valve heater control terminal B and PCM
terminal 2BL  



Short to power circuit between PCV valve heater fitting terminal B and PCM 
terminal 2AU  



Open circuit between PCV valve heater control terminal B and PCM terminal 
2BL  



Open circuit between PCV valve heater fitting B and PCM terminal 2AU  



Connector or terminal malfunction  



Damaged PCV heater assembly  

 

2008 Mazda CX-9 Grand Touring 

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

  

Microsoft 

 

Sunday, November 15, 2009 10:08:39 AM

Page 248 

© 2005 Mitchell Repair Information Company, LLC.