Details On DTCs

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

DTC P0140:00 (PCM, SKYACTIV-G, US) DETECTION CONDITION AND POSSIBLE CAUSE

Description	HO2S circuit no activity detected
Detection condition	Determination conditions	With the estimated temperature of the HO2S element exceeding the specified value, a condition in which the HO2S signal voltage is less than the specified value continues for the specified period.
	Preconditions	Battery voltage: above 11 V^1 The following DTCs are not detected: HO2S: P0137:00 and P0138:00 ECT sensor No. 1: P0117:00 and P0118:00 MAF sensor: P0100:00, P0101:00 and U060F:00 ^1 : Standard can be verified by displaying PIDs using M-MDS
	Drive cycle	2
	Self test type	CMDTC self test
	Sensor used	HO2S
Fail-safe function		Not applicable
Vehicle status when DTCs are output		Not applicable
Possible cause		HO2S signal line error HO2S connector or terminals malfunction PCM connector or terminals malfunction Short to ground in HO2S signal circuit Open circuit in HO2S signal circuit HO2S incorrect installation HO2S malfunction Exhaust gas leakage from exhaust system (between A/F sensor and HO2S) Insufficient engine compression HO2S heater malfunction PCM malfunction
Courtesy of MAZDA MOTORS CORP.