Service bulletin 01-004-20-3684a

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
Type	Service bulletin
NHTSA id	10176962
Published by NHTSA	2020-07-02
Manufacturer's number	01-004-20-3684a
Manufacturer's date	2020-06-22
NHTSA component	POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM); ENGINE AND ENGINE COOLING; ELECTRICAL SYSTEM:SOFTWARE

NHTSA's summary

Some customers may experience the master warning light turning on and a lack of power with DTC P2BF6:00 (Exhaust shutter valve position sensor circuit low input (1DC)) stored in memory. The PCM software has been modified to avoid the unnecessary warning light illumination and power restriction with no modification to the cylinder deactivation function and the error detection logic has been changed not to detect false error under low voltage during cranking.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Electrical system, Engine, Transmission and driveline, Automatic transmission, Software, Transmission control module

Trouble codes named

P2BF6

Vehicles listed
MAZDA MAZDA3	2019, 2020

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
19V497000	2019-06-27. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM); ENGINE

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
SA-038-22	2022-07-06. Service bulletin. Service part Automatic Transaxles (ATX) manufactured on or after July, 2018 are shipped with a blank TCM that requires configuration.
SA-004-22b	2022-06-04. Service bulletin. Customers having MAZDA CONNECT concerns should have their vehicle repaired using the following repair procedure.
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.
SA-023-21	2021-04-06. Service bulletin. Some customers may complain about any of the following: Warning light, Warning message, Headlight(s) inoperative, Cannot shift out of Park, Many DTC's stored, Module communication errors
SA-003-20f	2021-01-06. Service bulletin. IMPORTANT NOTE: Some 2020 Mazda3 vehicles may have incorrect infotainment software version 10042 installed. The incorrect software will cause MyMazda App Connected Vehicle enrollment errors. Go to SSPC1. Some customers may complain about any of the following: Infotainment Center Display does not provide the Authorization Code during the MyMazda App Connected Vehicle enrollment (and Software Update Error message on 2020 Mazda3 only). Remote function(s) inoperative. Engine Start / Stop, Door Lock / Unlock, Lights ON / OFF
07-006-20-3758	2021-01-05. Service bulletin. Some customers may complain that after accelerating in hot weather, the A/C blows warm air for a longer time than other models. This is caused by improper control software of the PCM not allowing the A/C compressor to resume properly after acceleration. To eliminate this concern, the control software of the PCM has been modified.
05-002-20-3704b	2021-01-05. Service bulletin. Some customers may complain about a surging at low speeds and during acceleration. This surging is in the longitudinal direction, felt about 2 cycles per second, and occurs in the locked up 1st gear. This may be caused by the torque fluctuation and the torsional resonance in the torque converter. To correct this concern, the PCM software has been modified to reduce the torque fluctuation.
SA-031-20j	2020-12-04. Service bulletin. IMPORTANT NOTE: Some 2020 Mazda3 vehicles may have incorrect infotainment software version 10042 installed. The incorrect software will cause MyMazda App Connected Vehicle enrollment errors. Go to SSPC1. Some customers may complain about any of the following: Infotainment Center Display does not provide the Authorization Code during the MyMazda App Connected Vehicle enrollment (and Software Update Error message on 2020 Mazda3 only). Remote function(s) inoperative. Engine Start / Stop, Door Lock / Unlock, Lights ON / OFF
SA-031-20i	2020-12-04. Service bulletin. IMPORTANT NOTE: Some 2020 Mazda3 vehicles may have incorrect infotainment software version 10042 installed. The incorrect software will cause MyMazda App Connected Vehicle enrollment errors. Go to SSPC1. Some customers may complain about any of the following: Infotainment Center Display does not provide the Authorization Code during the MyMazda App Connected Vehicle enrollment (and Software Update Error message on 2020 Mazda3 only). Remote function(s) inoperative. Engine Start / Stop, Door Lock / Unlock, Lights ON / OFF
09-013-20-3663c	2020-12-03. Service bulletin. When the Telematics Communication Unit (TCU) has been replaced or reprogrammed and the software is updated to ones shown below, DTC U2050:55-TCU (Activation of remote control not implemented) may be stored in memory with the message “In-Vehicle Network Malfunction” displayed in the multi-information display. This is caused by a communication error between the TCU, the Connectivity Master Unit (CMU), and the Body Control Module (BCM) when the control software in them are not of the version being ready for activation of connected service. To correct this concern, the control software of the TCU, CMU and BCM have been modified.