Mazda 3 - Dtc P0037 [Lf]

Mazda 3 Workshop Manual – Engine + Wiring Diagrams + Diagnostic Trouble Codes
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(See FRONT HEATED OXYGEN SENSOR
(HO2S) INSPECTION [LF].)
• Is the front HO2S heater normal?
5
INSPECT PCM TERMINAL
• Disconnect the PCM connector.
• Inspect for poor connection (such as
damaged/pulled-out pins, corrosion).
• Is there any malfunction?
Yes
Repair the terminal, then go to Step 7.
No
Go to the next step.
6
INSPECT FRONT HO2S HEATER CONTROL
CIRCUIT FOR SHORT TO POWER SUPPLY
• Turn the ignition switch to the ON position
(Engine off).
• Measure the voltage between front HO2S
terminal D (wiring harness-side) and body
ground.
• Is the voltage B+?
Yes
Repair or replace the wiring harness for
shot to power circuit, then go to the next
step.
No
Go to the next step.
7
VERIFY TROUBLESHOOTING OF DTC
P0032 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.
8
VERIFY AFTER REPAIR PROCEDURE
• Perform the "After Repair Procedure".
(See AFTER REPAIR PROCEDURE [LF].)
• Are any DTC present?
Yes
Go to the applicable DTC troubleshooting.
(See DTC TABLE [LF].)
No
Troubleshooting completed.
DTC P0037 [LF]
B3E010201084W03
DTC P0037
Rear HO2S heater circuit low input
DETECTION
CONDITION
• The PCM monitors the rear HO2S heater control signal at PCM terminal
2C. If the PCM turns the rear HO2S heater off but the rear HO2S heater
circuit has low voltage, the PCM determines that the rear HO2S heater circuit
has malfunction.