Mazda RX-8 Workshop Manual page 504

INSPECT A/F SENSOR HEATER
4
Inspect the A/F sensor heater.
(See AIR FUEL RATIO (A/F) SENSOR
INSPECTION
Is there any malfunction?
INSPECT A/F SENSOR HEATER POWER SUPPLY CIRCUIT
5
FOR SHORT TO GROUND OR OPEN CIRCUIT
A/F sensor connector is disconnected.
Turn the ignition switch to the ON position
(engine off).
Measure the voltage between A/F sensor
terminal C (wiring harness-side) and body
ground.
Is the voltage B+?
INSPECT A/F SENSOR HEATER CONTROL CIRCUIT FOR
6
SHORT TO GROUND
A/F sensor connector is disconnected.
Turn the ignition switch off.
Inspect for continuity between A/F sensor
terminal D (wiring harness-side) and body
ground.
Is there continuity?
INSPECT PCM CONNECTOR FOR POOR CONNECTION
7
Turn the ignition switch off.
Disconnect the PCM connector.
Inspect for poor connection (such as
[13B-MSP].)
YesReplace the A/F sensor, then go to Step 9.
(See AIR FUEL RATIO (A/F) SENSOR
REMOVAL/INSTALLATION
No Go to the next step.
YesGo to the next step.
No Inspect the A/F sensor heater related fuse.
If the fuse is melt:
If the fuse is deterioration:
If the fuse is normal:
Go to Step 9.
YesIf the short to ground circuit could be detected:
Repair or replace the wiring
harness for a possible short to
ground.
If the short to ground circuit could not be detected:
Replace the PCM (short to ground
in the PCM internal circuit).
(See PCM
REMOVAL/INSTALLATION [13B-
MSP].)
Go to Step 9.
No Go to the next step.
YesRepair or replace the connector and/or terminals,
then go to Step 9.
No Go to the next step.
[13B-MSP].)
Repair or replace
the wiring
harness for a
possible short to
ground.
Replace the fuse.
Replace the fuse.
Repair or replace
the wiring
harness for a
possible open
circuit.