U0300 on the 2020 Mazda Mazda3
The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.
Nobody has written a description of this code yet.
| SA-003-22d | 2022-04-06. Service bulletin. Mazda3 and CX-30: Prior to February 8, 2022, some vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) and cannot be erased after a BCM replacement or MDARS BCM software update (NOT with BCM update for SSPC5 or 4621B using MDRT). This is caused by a BCM-VCM software error. MX-30: Some MX-30 vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) and cannot be erased after a BCM replacement or MDARS BCM software update. This is caused by a BCM-VCM software error. Mazda is aware of the issue and is working on a resolution. If there is an issue with this concern, Mazda recommends putting customer in a loaner vehicle at this time. *DO NOT perform BCM software update with MDARS until further notice. *This SA will be updated with the newest repair information as it becomes available. |
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| SA-003-22c | 2022-04-06. Service bulletin. Mazda3 and CX-30: Prior to February 8, 2022, some vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) and cannot be erased after a BCM replacement or MDARS BCM software update (NOT with BCM update for SSPC5 or 4621B using MDRT). This is caused by a BCM-VCM software error. MX-30: Some MX-30 vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) and cannot be erased after a BCM replacement or MDARS BCM software update. This is caused by a BCM-VCM software error. Mazda is aware of the issue and is working on a resolution. If there is an issue with this concern, Mazda recommends putting customer in a loaner vehicle at this time. •DO NOT perform BCM software update with MDARS until further notice. •This SA will be updated with the newest repair information as it becomes available. |
| SA-003-22b | 2022-03-04. Service bulletin. CX-30. Mazda3: Prior to February 8, 2022, some vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) and cannot be erased after a BCM replacement or MDARS BCM software update (NOT with BCM update for SSPC5 or 4621B using MDRT). This is caused by a BCM-VCM software error. Customers having this concern should have their vehicle repaired using the following repair procedure. MX-30: Some MX-30 vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) and cannot be erased after a BCM replacement or MDARS BCM software update. This is caused by a BCM-VCM software error. Mazda is aware of the issue and is working on a resolution. If there is an issue with this concern, Mazda recommends putting customer in a loaner vehicle at this time. DO NOT perform BCM software update with MDARS until further notice. This SA will be updated with the newest repair information as it becomes available. |
| SA-003-22a | 2022-03-04. Service bulletin. Some vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) after a BCM replacement or MDARS BCM software update (NOT with BCM update for SSPC5 or 4621B using MDRT) and the DTC cannot be erased. This is caused by a BCM-VCM software error. Mazda is aware of the issue and is working on a resolution. If there is an issue with this concern, contact Hotline for newest repair information. DO NOT perform BCM software update with MDARS until further notice, including CSP06 and CSP07. This SA will be updated with the newest repair information as it becomes available. |
| SA-003/22 | 2022-02-04. Service bulletin. Some vehicles may store DTC U0300:57 (Body control module (BCM) internal malfunction) after a BCM replacement or MDARS BCM software update (NOT with BCM update for SSPC5 or 4621B using MDRT) and the DTC cannot be erased. This is caused by a BCM-VCM software error. Mazda is aware of the issue and is working on a resolution. If there is an issue with this concern, Mazda recommends putting customer in a loaner vehicle at this time. •DO NOT perform BCM software update with MDARS until further notice, including CSP06 and CSP07. •This SA will be updated with the newest repair information as it becomes available. |
5 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.