Mazda CX-7 2007 Workshop Manual page 70

End Of Sie
DTC P0031[L3 WITH TC]
DTC P0031 Front HO2S heater circuit low input
• The PCM monitors the front HO2S heater output voltage. If the PCM turns the front HO2S heater off or on
but the front HO2S heater circuit voltage remains low the PCM determines that the front HO2S heater
circuit has a malfunction.
Note
• The front HO2S heater is controlled by a duty signal.
DETECTION
Diagnostic support note
CONDITION
• This is a continuous monitor (HO2S heater).
• The MIL illuminates if the 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 the PCM detects the above malfunction condition during the first drive
cycle.
• FREEZE FRAME DATA is available.
• DTCs are stored in the PCM memory.
• Front HO2S heater malfunction
• Connector or terminal malfunction
• Open circuit in the wiring harness between main relay and front HO2S terminal 2B
POSSIBLE
• Short to ground in the wiring harness between main relay and front HO2S terminal 2B
CAUSE
• Open circuit in the wiring harness between front HO2S terminal 2D and PCM terminal 2C
• Short to ground in the wiring harness between front HO2S terminal 2D and PCM terminal 2C
• PCM malfunction
MAIN RELAY
3
2B
WIRING HARNESS-SIDE CONNECTOR
Diagnostic procedure
STEP
1 VERIFY FREEZE FRAME DATA AND
DIAGNOSTIC MONITORING TEST RESULTS
HAVE BEEN RECORDED
• Have the FREEZE FRAME DATA and
DIAGNOSTIC MONITORING TEST RESULTS
(HO2S heater related) been recorded?
01-02–28
ON-BOARD DIAGNOSTIC [L3 WITH TC]
FRONT HO2S HEATER
5
3
2D
FRONT HO2S
1C 1A 2C 2A
1D 1B 2D 2B
INSPECTION
4
PCM
WIRING HARNESS-SIDE CONNECTOR
2BE 2BA 2AW 2AS 2AO 2AK 2AG 2AC 2Y 2U 2Q 2M
2BF 2BB 2AX 2AT 2AP 2AL 2AH 2AD 2Z 2V 2R 2N
2BG 2BC 2AY 2AU 2AQ 2AM 2AI 2AE 2AA 2W 2S 2O
2BH 2BD 2AZ 2AV 2AR 2AN 2AJ 2AF 2AB 2X 2T 2P
Yes Go to the next step.
No Record the FREEZE FRAME DATA and DIAGNOSTIC
MONITORING TEST RESULTS on the repair order, then
go to the next step.
id010239802000
PCM
6
2C
2I 2E 2A
2J 2F 2B
2K 2G 2C
2L 2H 2D
ACTION