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 P2251:00 (PCM, SKYACTIV-G, US) DETECTION CONDITION AND POSSIBLE CAUSE

Description	Open circuit between A/F sensor terminal D and PCM terminal 1S
Detection condition	Determination conditions	The following conditions are met: A/F sensor element impedance is specified value or more A/F sensor terminal F voltage (B+ terminal) is less than specified value or unstable.
	Preconditions	Battery voltage: 11-18 V¹ A/F sensor is activated. The following DTCs are not detected: A/F sensor terminal F voltage (B+ terminal) is less than specified value: A/F sensor heater: P0031:00 and P0032:00 A/F sensor terminal F voltage (B+ terminal) is unstable: Internal PCM malfunction: P064D:00 ^1 : Standard can be verified by displaying PIDs using M-MDS
	Drive cycle	2
	Self test type	CMDTC self test, KOER self test
	Sensor used	A/F sensor
Fail-safe function	Not applicable
Vehicle status when DTCs are output	Not applicable
Possible cause	A/F sensor connector or terminals malfunction PCM connector or terminals malfunction Open circuit in A/F sensor signal circuit A/F sensor malfunction PCM malfunction
Courtesy of MAZDA MOTORS CORP.