Mazda 3 - Page 261

Mazda 3 Workshop Manual – Engine + Wiring Diagrams + Diagnostic Trouble Codes
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261
• Inspect the front HO2S heater.
(See FRONT HEATED OXYGEN SENSOR
(HO2S) INSPECTION [LF].)
• Is the front HO2S heater normal?
No
Replace the front HO2S, then go to Step 9.
5
INSPECT POWER CIRCUIT OF FRONT HO2S
HEATER FOR OPEN CIRCUIT
• Turn the ignition switch to the ON position
(Engine off).
• Measure voltage between front HO2S terminal
C (harness-side) and body ground.
• Is the voltage B+?
Yes
Go to the next step.
No
Repair or replace the wiring harness for
open circuit, then go to Step 9.
6
INSPECT POOR CONNECTION OF PCM
CONNECTOR
• Turn the ignition switch off.
• Disconnect the PCM connector.
• Inspect for poor connection (such as
damaged/pulled-out pins, corrosion).
• Is there any malfunction?
Yes
Repair terminal, then go to Step 9.
No
Go to the next step.
7
INSPECT CONTROL CIRCUIT OF FRONT
HO2S HEATER FOR SHORT TO GROUND
• Inspect for continuity between front HO2S
terminal D (wiring harness-side) and body
ground.
• Is there continuity?
Yes
Repair or replace the wiring harness for
short to ground, then go to Step 9.
No
Go to the next step.
8
INSPECT CONTROL CIRCUIT OF FRONT
HO2S HEATER FOR OPEN CIRCUIT
• Inspect for continuity between front HO2S
terminal D (wiring harness-side) and PCM
terminal 2G.
• Is there continuity?
Yes
Go to the next step.
No
Repair or replace the wiring harness for
open circuit, then go to Step 9.
9
VERIFY TROUBLESHOOTING OF DTC P0031
COMPLETED
• Make sure to reconnect all disconnected
connectors.
• Clear the DTC from the PCM memory using
the WDS or equivalent.
• Perform the HO2S heater, HO2S, and TWC
Repair Verification Drive Mode. (See OBD
DRIVE MODE [LF].)
• Is the PENDING CODE for this DTC present?
Yes
Replace the PCM, then go to the next
step.
(See PCM REMOVAL/INSTALLATION
[LF].)
No
Go to the next step.