DTC P0031-00: A/F Sensor Heater Control System: Low Input (PYUL)

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P0031-00 (PCM (PYUL)) DETECTION CONDITION AND POSSIBLE CAUSE

System malfunction location	A/F sensor heater control system: Low input
Detection condition	When the PCM controls the A/F sensor heater, the voltage input to the PCM is excessively low.
Fail-safe	Feedback correction of fuel injection control is stopped. Inhibits engine-stop by i-stop control.
Vehicle status when DTCs are output	Not applicable
Repeatability verification procedure	Clear the DTC recorded in the memory. (See CLEARING DTC ) Perform the KOER self test. (See DTC INSPECTION )
Inspection/action procedure	Proceed with the inspection/action in the order from Step 1 below. After part repair or replacement, perform the repeatability verification procedure and perform a DTC inspection. (See DTC INSPECTION ) If the DTC inspection indicates the same DTC again, go to the next step. Inspect the wiring harness (including connector/terminal) between the sub relay and the A/F sensor. Purpose/reason (possible cause) Malfunction in wiring harness (including connector/terminal) between sub relay and A/F sensor Referred to service information item (See CIRCUIT INSPECTION .) (See CONNECTOR INSPECTION .) Inspect the wiring harness (including connector/terminal) between A/F sensor and the PCM. Purpose/reason (possible cause) Malfunction in wiring harness (including connector/terminal) between A/F sensor and PCM Referred to service information item (See CIRCUIT INSPECTION .) (See CONNECTOR INSPECTION .) Inspect the A/F sensor. Purpose/reason (possible cause) A/F sensor malfunction (A/F sensor heater malfunction) Referred to service information item (See AIR FUEL RATIO (A/F) SENSOR INSPECTION .) Replace the PCM. Purpose/reason (possible cause) PCM malfunction (no other possible malfunction considered) Referred to service information item (See PCM REMOVAL/INSTALLATION [H3T] )
Refer to SYSTEM WIRING DIAGRAMS Courtesy of MAZDA MOTORS CORP.
1	Battery
2	Sub relay
3	A/F sensor (A/F sensor heater)
4	PCM
Function explanation (DTC detection outline)	Not applicable