Service bulletins for the 2020 Mazda Mazda3
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.
726 on file from NHTSA, as of 2026-10-19.
By type
By component
By trouble code
By topic
| SA-027-21b | 2021-10-05. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. MAZDA CONNECT Symptom Troubleshooting (7th Generation Vehicles). Customers having MAZDA CONNECT concerns should have their vehicle repaired using the following repair procedure |
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| SA-047-21 | 2021-10-05. Service bulletin. ENGINE AND ENGINE COOLING. If you receive a customer concern about the CHECK ENGINE light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, the cylinder deactivation oil control valve may be plugged with plastic debris from the oil filter wrapper. The debris may enter the center of the oil filter when poking a hole in the filter wrapper during removal, and then travel through the engine and plug the cylinder deactivation oil control valve. |
| SA-013-21g | 2021-10-05. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM; EQUIPMENT ADAPTIVE/MOBILITY. 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. Remote function(s) inoperative. Engine Start / Stop, Door Lock / Unlock, Lights ON / OFF, MAZDA CONNECT connected vehicle reception strength icon shows "X" or " ". Confirm the customer's phone and vehicle have good to strong reception during the concern as shown in the table below. If the reception is weak, move the vehicle to a location where the reception is good to strong as shown in the table, then try to get the Authorization Code and/or operate the remote functions before proceeding to the Repair Procedure if there is still an issue. If the reception is good to strong, proceed to the Repair Procedure. |
| SA-004-21c | 2021-10-05. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. When the Telematics Control Unit (TCU) replacement is necessary due to a failure, use MDARS to activate the new TCU after replacement. Use the information in this service alert to initialize the new TCU until the procedure on MGSS is updated. CAUTION: DO NOT swap TCU with another vehicle as the TCU is VIN locked after activation. A TCU swap with another vehicle will disable Connected Services on both vehicles. If TCU activation is not performed, connected vehicle functions will not operate. This will have a negative impact on the customer because they will need to return to the dealer for repairs. |
| MT-002-21 | 2021-10-02. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING. Ethanol is becoming a common additive in gasoline. Gasoline containing ethanol is likely available at your local gasoline station. Typical blends of ethanol include E10 and E85. E10: A blend of 10% ethanol and 90% gasoline, E85: A blend of 85% ethanol and 15% gasoline, All Mazda vehicles can run on gasoline containing up to 10% ethanol (E10) but only some 1999-2001 B3000 trucks can run on gasoline with more than 10% ethanol blended. E10 compatible vehicles: All Mazda vehicles. E85 compatible vehicles: 1999-2001 B3000 Mazda trucks with the 8th VIN digit is V. What if a customer puts E85 in there Mazda vehicle? Symptoms include: Rough Running, Lean Codes, Misfires and/or misfire codes, Lack of power, Poor fuel economy, Spark knock, Mechanical engine damage. |
| 09-026-21-3817 | 2021-10-02. Service bulletin. STRUCTURE:BODY:DOOR; EQUIPMENT. Some vehicles may experience white-streak stains appearing on the front door that look like they seeped out from under the outer mirror base. This is caused by water intruding from gaps of the outer mirror body and/or the hinge of the outer mirror, and corrosion occurring on the aluminum die-cast inner base in the outer mirror. Water, including white-salty corrosion, may drip out from gaps under the outer mirror base resulting in white stains on the front door. |
| 01-011-21-3800a | 2021-10-02. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; ENGINE AND ENGINE COOLING. Some customers may experience the CHECK ENGINE light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: The engine takes longer to warm up, The engine temperature gauge fluctuates, The low coolant temperature indicator (blue) light stays on longer or comes on while driving, Poor heater performance, especially at idle. NOTE: Vehicles with SKYACTIV-G 2.5T are not applicable. Due to production variety of the failsafe thermostat integrated in the coolant control valve, engine coolant may enter into a dry hollow in the failsafe thermostat, resulting in unintended opening of the failsafe thermostat at lower temperatures (104-176 °F (40-80 °C)). To eliminate this concern, the production process of the coolant control valve has been modified. |
| SA-031-21a | 2021-09-03. Service bulletin. ENGINE AND ENGINE COOLING:EXHAUST SYSTEM. A new cylinder head assembly for service parts has been newly established for SKYACTIV-G 2.5 with cylinder deactivation when replacement is needed. Valves, valve springs, valve spring seats, and cotters (IN/EX) are included in the new assembly. |
| 01-006-21-3779a | 2021-09-03. Service bulletin. ELECTRICAL SYSTEM:12V/24V/48V BATTERY; ENGINE AND ENGINE COOLING. This service bulletin provides testing and charging procedures in order to promote proper battery maintenance, to deliver new vehicles with fully charged batteries, and to reduce unnecessary battery replacement cost. For new vehicles in stock at the dealer, inspect and maintain the battery periodically according to the repair procedure. |
| 09-021-21-3818a | 2021-08-24. Service bulletin. EQUIPMENT:ELECTRICAL:INFOTAINMENT. AUDIO, NAVIGATION AND PHONE CONCERNS WITH MAZDA CONNECT INFOTAINMENT SYSTEM (6TH GENERATION). All Mazda Connect vehicles in new car inventory must be updated to the software version listed below in this TSB as part of the New Car Ready Step 3 process. Make sure the new vehicle specialist receives a copy of this bulletin. Some vehicles may experience the symptoms mentioned below, which can be fixed with the latest software update (Version 70.00.367 or later). NOTE: For 2016 CX-9 with version earlier than 59.00.441, the tachometer function will be removed from the Active Driving Display as part of Mazdas continuing efforts to improve safety and reduce driver distraction. |
| 09-025-21-3824 | 2021-08-24. Service bulletin. EQUIPMENT. This service bulletin provides information regarding the proper use of the driver’s floor mat to avoid any potential interference with the foot pedals. The following are possible causes of floor mat interference, which can be avoided with proper usage. |
| SA-044-21 | 2021-08-03. Service bulletin. SERVICE BRAKES, HYDRAULIC. When switching to the maintenance mode, U3000:53 and the related DTCs are stored, but the DTCs will not be cleared automatically after finishing the maintenance mode. It is necessary to clear the DTCs completely after performing the brake system maintenance mode. DTC codes: U3000:53, C0021:52, U0415:68 |
| SA-043-21 | 2021-08-03. Service bulletin. EQUIPMENT. If both key transmitters are lost, MDARS key programming functions may be missing, not allowing new key transmitters to be added. Use the procedure below to program new key transmitters when both keys are lost. |
| 09-022-21-3815 | 2021-08-02. Service bulletin. VISIBILITY. Some customers may complain that the frequency of replenishing the window washer liquid is higher than expected, or they may complain of leakage at around the washer motor (1).This is caused by a crack that may occur at the joint section of the washer motor housing due to an inappropriate assembly process. To eliminate this concern, the design of the washer motor has been modified to not have a joint section. |
| 09-020-21-3804 | 2021-08-02. Service bulletin. STRUCTURE. Some vehicles may exhibit water leaking into the passenger compartment from the rear door through the bottom of the service hole behind the rear door trim during rain or when washing the vehicle. This is caused by one of the following: Since the material of the seal rubber is not resistant to surfactants, the rubber deteriorates when the vehicle is washed and allows water to penetrate into the seal rubber of the service hole cover. The lower tabs of the service hole cover may not have been completely engaged at the factory. To eliminate this concern, the service-hole cover has been modified. NOTE: It is a tentative change. |
| 02-002-21-3769a | 2021-08-02. Service bulletin. WHEELS. Some automotive cleaning products contain strong acid or alkali. When these types of cleaners are used to clean the wheels on Mazda vehicles, the chemicals contents penetrate the clear coating of the wheel surface and damage the paint under the clear coating. The damaged area has the appearance of dark stains or discoloration. |
| SA-004-21b | 2021-07-02. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; ELECTRICAL SYSTEM. When the Telematics Control Unit (TCU) replacement is necessary due to a failure, use MDARS to activate the new TCU after replacement. Use the information in this service alert to initialize the new TCU until the procedure on MGSS is updated. CAUTION: If TCU activation is not performed, connected vehicle functions will not operate. This will have a negative impact on the customer because they will need to return to the dealer for repairs. |
| SA-029-21a | 2021-07-02. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. APPLE CARPLAY / ANDRID AURO FREQUENTLY ASKED QUESTIONS (FAQ) The following vehicles are not equipped with Apple CarPlay / Android Auto, but it can be activated using MDARS. See Activation instructions on MGSS -> Infotainment -> MAZDA CONNECT Updates -> Apple Carplay / Android Auto MDARS Activation Instructions |
| SA-027-21a | 2021-07-02. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. MAZDA CONNECT Symptom Troubleshooting (7th Generation Vehicles). Customers having MAZDA CONNECT concerns should have their vehicle repaired using the following repair procedure |
| SA-013-21f | 2021-07-02. Service bulletin. ENGINE AND ENGINE COOLING; EXTERIOR LIGHTING; EQUIPMENT ADAPTIVE/MOBILITY. 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, MAZDA CONNECT connected vehicle reception strength icon shows "X" or " ". |
| SA-012-21f | 2021-07-02. Service bulletin. ENGINE AND ENGINE COOLING; SERVICE BRAKES. MAZDA CONNECTED SERVICES - FREQUENTLY ASKED QUESTIONS (FAQ): Index: General Questions, Setup and Getting Started, Registration / Enrollment, WI-FI General Information, WI-FI How-To, WI-FI Trial Period, Interacting With The App, Service Issues, Troubleshooting, Reception Level Inspection, Dealer Processes, Conditions for Remote Engine Start Will Not Function, Conditions for Remote Engine Start Function Will turn engine OFF, Educational Videos, Resources |
| SA-030-21a | 2021-07-02. Service bulletin. EQUIPMENT. There are currently 2 methods for cutting a new auxiliary key blank. A. Auxiliary Key Trace Cut Method B. Auxiliary Key Code Cut Method A. Auxiliary Key Trace Cut Method If only one auxiliary key is lost/missing, some key cutting machines can trace cut a new key blank. 1. Trace cut the new auxiliary key blank(s). B. Auxiliary Key Code Cut Method If both auxiliary keys are lost/missing, use this method for cutting new auxiliary key blank(s). 1. Confirm you have access to a Mazda approved key cutting machine. See “Mazda Approved Key Cutting Machine” table. |
| SA-039-21 | 2021-07-02. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT ADAPTIVE/MOBILITY. Some customer may experience all of the following when turning the ignition ON under hot weather conditions such as parking under the hot sun for some period of time: i-ACTIVSENSE warning light ON (1), Smart Brake Support (SBS) indicator light ON (2), "Excessive Camera Temp. Drive Safely" or "Safety and Driver Support Systems Temporarily Disabled" warning messages, DTC B14F9:00 stored in memory, DTC B14F9:00 cannot be found on MGSS, therefore repair cannot be performed. |
| SA-040-21 | 2021-07-01. Service bulletin. VISIBILITY:POWER WINDOW DEVICES AND CONTROLS. Some vehicles may experience exterior trim heat damage when parked near a glass building or Low-E windows. This may be caused by the sun's reflection. |
| SA-041-21 | 2021-07-01. Service bulletin. EQUIPMENT. Accessory instructions can be found on OneMazda under Dealer Resources - Parts & Accessories. The links provided below can be used for quick access: For 2016 models and newer: NOTE: Instructions are found under the "Attachments" section once a part is selected. Accessories E-catalog For models prior to 2016: Accessory Parts and Installation Instructions |
The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.