Mazda CX-9 Grand Touring. Manual - part 298

DTC P1289 [MZI-3.7] 

DTC P1289 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

7



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?  

[MZI-3.7] .)

No

Go to the next step.

8

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].)

No

Troubleshooting completed.

DTC P1289

CHT sensor circuit high input

DETECTION 

CONDITION 



Indicates a CHT sensor circuit open.  

POSSIBLE CAUSE 



Open circuit in wiring harness between CHT sensor terminal A and PCM 
terminal 2AL  



Open circuit in wiring harness between CHT sensor terminal B and PCM 
terminal 2AN  



Short to power supply in wiring harness between CHT sensor terminal B and 
PCM terminal 2AN  



CHT sensor malfunction  



Connector or terminal malfunction  

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:08:41 AM

Page 325 

© 2005 Mitchell Repair Information Company, LLC. 

DIAGNOSTIC PROCEDURE 

DTC P1289 (MZI-3.7) DIAGNOSTIC PROCEDURE 

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.

VERIFY RELATED REPAIR 
INFORMATION AVAILABILITY  

Perform repair or diagnosis according to the 
available Service Bulletins. 

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:08:41 AM

Page 326 

© 2005 Mitchell Repair Information Company, LLC. 

2



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



Is any related Service Bulletins 
available?  

Yes



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

No

Go to the next step.

3

INSPECT POOR CONNECTION OF CHT 
SENSOR CONNECTOR  



Turn the ignition switch off.  



Disconnect CHT sensor connector.  



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



Are there any malfunction?  

Yes

Repair or replace suspected part, then go to 
Step 8.

No

Go to the next step.

4

INSPECT CHT SENSOR SIGNAL 
CIRCUIT FOR SHORT TO POWER 
SUPPLY  



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



Measure the voltage between CHT 
sensor terminal B (wiring harness-side) 
and body ground.  



Is the voltage B+?  

Yes

Repair or replace suspected part, then go to 
Step 8.

No

Go to the next step.

5

INSPECT PCM CONNECTOR FOR 
POOR CONNECTION  



Disconnect the PCM connector.  



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



Are there any malfunction?  

Yes

Repair or replace suspected part, then go to 
Step 8.

No

Go to the next step.

6

INSPECT CHT SENSOR CIRCUIT FOR 
OPEN CIRCUIT  



Inspect the continuity between the 
following circuit: 



CHT sensor terminal A (wiring 
harness-side) and PCM terminal 
2AL (wiring harness-side).  



CHT sensor terminal B (wiring 
harness-side) and PCM terminal 
2AN (wiring harness-side).  



Are there continuity?  

Yes Go to the next step.

No

Repair or replace suspected part, then go to 

Step 8.

INSPECT CHT SENSOR  

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:08:41 AM

Page 327 

© 2005 Mitchell Repair Information Company, LLC. 

DTC P1290 [MZI-3.7] 

DTC P1290 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

7



Inspect the CHT sensor. (See 
CYLINDER HEAD 
TEMPERATURE (CHT) SENSOR 
INSPECTION [MZI-3.7] .)  



Is there any malfunction?  

Yes

Replace the CHT sensor, then go to the next 
step.

No

Go to the next step.

8

VERIFY TROUBLESHOOTING OF DTC 
P1289 HAS BEEN 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] .)

No

Go to the next step.

9

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].)

No

Troubleshooting completed.

DTC P1290

CHT sensor circuit low input

DETECTION 

CONDITION 



Indicates a CHT sensor circuit short to ground.  

POSSIBLE CAUSE 



Short to ground in wiring harness between CHT sensor terminal B and PCM 
terminal 2AN  



CHT sensor malfunction  



Connector or terminal malfunction  

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:08:41 AM

Page 328 

© 2005 Mitchell Repair Information Company, LLC.