Mazda 3 Workshop Manual page 261

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