Mazda 6 2002, Workshop Manual

Page: 209 / 1248

F–80
ON-BOARD DIAGNOSTIC
DTC P0038
A6E397001084W07
Diagnostic procedure
DTC P0038 Rear HO2S heater circuit high input
DETECTION
CONDITION
•
PCM monitors rear HO2S heater control signal at PCM terminal 4D. If PCM turns rear HO2S heater on but
rear HO2S heater circuit has high voltage, PCM determines that rear HO2S heater circuit has malfunction.
Diagnostic support note
•
This is a continuous monitor (O
2
sensor heater).
•
MIL illuminates if PCM detects the above malfunction condition in two consecutive drive cycles or in one
drive cycle while the DTC for the same malfunction has been stored in the PCM.
•
PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.
•
FREEZE FRAME DATA is available.
•
DTC is stored in PCM memory.
POSSIBLE
CAUSE
•
Short to power circuit between rear HO2S terminal D and PCM terminal 4D
•
Rear HO2S or PCM terminal is shorted
•
Rear HO2S heater malfunction
•
PCM malfunction
STEP INSPECTION ACTION
1 PERFORM DTC CONFIRMATION PROCEDURE
•
Perform DTC CONFIRMATION PROCEDURE.
(See
F–66 DTC CONFIRMATION
PROCEDURE .)
•
Is same DTC present?
Yes Go to next step.
No Intermittent concern exists. Go to INTERMITTENT
CONCERN TROUBLESHOOTING procedure.
(See
F–227 INTERMITTENT CONCERN
TROUBLESHOOTING .)
2 INSPECT REAR HO2S TERMINAL
•
Turn ignition key to OFF.
•
Disconnect rear HO2S connector.
•
Inspect for bent terminals
•
Is there any malfunction?
Yes Repair or replace terminal, then go to Step 6.
No Go to next step.
3 INSPECT REAR HO2S HEATER
•
Inspect rear HO2S heater.
(See
F–56 HEATED OXYGEN SENSOR
(HO2S) INSPECTION .)
•
Is rear HO2S heater okay?
Yes Go to next step.
No Replace the rear HO2S, then go to Step 6.