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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.

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Bulletins, newest first
15-001-20-36522020-01-23. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; VEHICLE SPEED CONTROL:CRUISE CONTROL. Some customers may complain about a shift shock and/or an engine RPM increase when setting the Mazda Radar Cruise Control (MRCC) system with no DTCs being stored. NOTE: This concern only occurs on vehicles equipped with a PCM manufactured by MITSUBISHI.This is caused by improper control logic of the PCM allowing the engine RPM increase for an instant right after setting the MRCC. To correct this issue, the PCM software has been modified.
02-002-20-36512020-01-23. Service bulletin. SUSPENSION; EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY. Some customers may complain of signs of oil on the struts or shock absorbers. In most cases the oil that is present is normal, and a result of the oil that remains on the shaft during the normal sweeping process of the shaft seal. Follow the inspection guidelines below to determine if the condition is a result of the normal sweeping process or a failure of the shaft seal.
SA-058-192019-12-21. Service bulletin. POWER TRAIN; UNKNOWN OR OTHER. WARRANTY GUIDELINES FOR RETURNED TRANSMISSION CORES. Be advised that the Mazda Remanufactured Transmission Center (MRTC) has found that up to 30% of the returned transmission cores either included the wrong transmission oil cooler, or the oil cooler was missing altogether. IMPORTANT NOTE: ALWAYS REMEMBER TO INCLUDE THE ORIGINAL OIL COOLER WITH THE RETURNED TRANSMISSION CORE!
SA-053-192019-12-21. Service bulletin. ENGINE AND ENGINE COOLING; POWER TRAIN. GUIDE LINES AND PHOTOS TO DETERMINE IF FLUID/OIL SEEPAGE OR LEAK IS SEVERE ENOUGH TO REQUIRE WARRANTY REPAIR OR TO CLEAN AND MONITOR. Some customer's might state that they notice fluid or oil leaking/dripping on the ground when the vehicle is parked. For this concern, inspect the vehicle for any trace of a fluid or oil leak and use the following examples as a guide to determine if it is severe enough to require a repair, or just to clean the area and monitor it at the next service.
SA-042-19a2019-12-21. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY. Customers having MAZDA CONNECT concerns should have their vehicle repaired using the following repair procedure.
02-007-19-36452019-12-21. Service bulletin. WHEELS. Some vehicles may exhibit corrosion of the wheel nuts. This is caused by torsional stress concentrating on the tip of the wheel nut because of the thin and long shape of the nut, which damages the coating and causes the corrosion. To correct this issue, the width across the flats of the wheel nuts have been changed from 17mm to 21mm.
SA-027-192019-12-20. Service bulletin. VISIBILITY; TRAILER HITCHES; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. Accessory instructions can be found in the Accessory eCatalog. https://ecatalog.trademotion.com/. Audio/Electrical, Exterior, Interior: - Mazda Mobile Start (MMS) - Remote Engine Start - Wireless Charging Pad - Mirror - Navigation - Rear Parking Sensors - Rear Seat Entertainment - Smartphone Screen Mirroring - Bumper Trim/Guards - Door Mirror Caps - Fog Lights - Moonroof Wind Deflector - Roof Rack - Side Window Deflectors - Splash Guards - Trailer Hitch - Thule Products - Wheels Locks - Aero Kit - Air Dam - Rear Spoiler - Tunnel Under Bars - Lower Arm Bar - Side Sill Extensions - Arm Rest - Illuminated Door sill Trim Plates - Interior Lighting
MT-002-192019-12-20. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT. If an engine assembly is replaced after a catastrophic internal mechanical failure, clean the intake manifold internally before installing a replacement engine assembly. If the intake manifold is not cleaned properly, the replacement engine may fail prematurely. Metallic debris from the old engine (with catastrophic internal mechanical failure) may rest inside the intake manifold. When the new engine assembly is installed, debris in the intake manifold will be ingested into the new engine and cause internal damage.
07-002-19-3616a2019-12-20. Service bulletin. EQUIPMENT; EQUIPMENT:APPLIANCE:AIR CONDITIONER; EQUIPMENT ADAPTIVE/MOBILITY. A musty/mildew type odor may come from the vents when the air conditioning (A/C) system is operating. It is most noticeable when the A/C is first turned ON. This odor is the result of mold growth in the A/C evaporator/cooling unit which is caused by condensation, dust, and pollen within the cooling unit. This condition is usually worse during high humidity conditions. “Mazda Air Cooling Coil Coating” is available to encapsulate the mold to reduce odors. If the product is properly applied, it can effectively reduce the musty/mildew odor for up to three years. NOTE: See parts information for Mazda Air Cooling Coil Coating and Kit part numbers.
01-022-19-36572019-12-20. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; ENGINE AND ENGINE COOLING. There is a concern that some water pumps are being replaced that are not faulty, due to signs of a very small coolant leak from the bleed hole. This Service Bulletin is to inform you about the water pump sealing mechanism and the criteria if replacement is necessary or not.
01-021-19-36492019-12-20. Service bulletin. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM); ENGINE AND ENGINE COOLING. Some customers may experience the CHECK ENGINE light ON with DTC P0012:00 (Electric variable valve timing control system: Over-retarded) stored in PCM memory. NOTE: This concern occurs only on the vehicles with PCMs manufactured by MITSUBISHI.This is caused by improper control logic of the PCM detecting a false error. To correct this issue, the PCM software has been modified. NOTE: The VVT actuator is damaged by the improper control logic.
09-036-19-3623a2019-12-20. Service bulletin. EQUIPMENT; EXTERIOR LIGHTING; VISIBILITY; EQUIPMENT ADAPTIVE/MOBILITY. Some customers may complain about an instrument cluster warning message "Auto Light System Malfunction. Turn On/Off Lights Manually". DTC B10AD:09 (Humidity sensor/solar radiation sensor/auto light sensor/rain sensor malfunction) may also be stored with the exterior light warning indicator light ON. This is caused by the rain sensor detecting a temperature higher than the operation range and temporarily stopping the auto light system. As a fail-safe, the low beam headlights are turned on. The auto light system will start to operate normally when the A/C is turned on and the interior temperature drops. To correct this concern, the heat resistance performance of the rain sensor has been enhanced.
01-020-19-36412019-12-05. Service bulletin. ENGINE AND ENGINE COOLING. Some vehicles may exhibit an excessive body vibration when idling or driving after being left in extremely cold weather (-20°F or below) for a long time. This is caused by the No.1 engine mount (1) rubber hardening due to material characteristics. NOTE: This concern only happens in extremely cold weather, therefore this TSB is only applicable for extremely cold regions.To correct this concern, the cold environment performance of the No.1 engine mount rubber has been increased by changing the rubber material.
SA-050-192019-11-24. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; FORWARD COLLISION AVOIDANCE. FSC dynamic aiming (mid-drive aiming) may not complete if the vehicle is driven on a road as described below: • The road lane markings are covered by snow and are not visible. • There are no road lane markings on the road surface. • The road is winding and the vehicle cannot drive straight (300 m / 984 ft or more turning radius is required). FSC dynamic aiming is completed if the following conditions are met: 1. "Forward Sensing Camera Calibration Mode" message (1) on instrument cluster MID disappears. 2.The i-ACTIVSENSE warning light (2) turns off. 3. Steps 1 and 2 are completed within 20 minutes from start of aiming.
MT-004-192019-11-24. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; ELECTRICAL SYSTEM. Some customers may complain about: • Intermittent engine no start • Instrument cluster red security indicator light ON • Engine Start/Start Button Amber indicator light flashing • Battery discharge • Electrical relay buzzing noise • DTC B13D3:94 (Communication error with remote transmitter) stored.This may be caused by: • A key in a purse near a cell phone. The cell phone radio waves may interrupt the immobilizer system. • An aftermarket cell phone charger. The charger may produce electrical noise that interrupts the immobilizer system. • An aftermarket GPS tracker. Some aftermarket devices that are wired to the vehicles’s wiring harness may create unusual electrical symptoms.
DRW272019-11-21. Service bulletin. STRUCTURE:BODY; VISIBILITY; EQUIPMENT. On certain subject vehicles, it is possible that the chrome plated window moldings may be dirty or have rust spots. The subject vehicles were parked outside when Typhoon No.17 passed through Hiroshima and Hofu, Japan, and might have been exposed to misty seawater caused by a heavy wind. The sampling inspection revealed that the chrome plated window moldings of certain vehicles became rusty due to seawater mist. All of the potentially affected vehicles have been rinsed with fresh water prior to shipment. OUTLINE OF REPAIR: If the vehicle has a port hangtag with direction to repair a chrome molding, but does not show DRW27 in eMDCS Warranty Vehicle Inquiry, please contact Dealer Recall Help on MXConnect > Warranty. Look for a hangtag placed in the vehicle by the port. If one is found and the vehicle displays DRW27 in eMDCS, inspect the affected molding(s) and perform a secondary cleaning with polishing compound. If any rust or pitting is still present, replace that affected molding(s) with new parts(s).
SA-046-192019-11-21. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. On the 2019 Mazda3 (BP) and and all 2020 Mazda vehicles (except CX-3), the CR2032 button cell battery is required for the new type remote transmitter. If it is mistakenly replaced with the conventional CR2025 used in the previous type remote transmitter, it may cause a malfunction. Verify the button cell battery type before replacing it.
SA-019-192019-11-21. Service bulletin. EQUIPMENT; FORWARD COLLISION AVOIDANCE: SENSING SYSTEM: RADAR; ELECTRICAL SYSTEM; EQUIPMENT ADAPTIVE/MOBILITY. Some vehicles may experience M-MDS (MDARS) showing the front radar dynamic aiming is incomplete, although the procedure is completed. This is caused by faulty front radar software logic and a mass production change is planned. If the screen below is displayed after the front radar dynamic aiming is performed, check the vehicle using the following inspection procedure.
SA-045-192019-11-01. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Currently, Mazda does not have a way to cut the auxiliary keys for the new style remote transmitter as they use a different key code than the previous transmitter key. Follow the repair procedure if one or both auxiliary keys are lost:
DRW262019-10-30. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; LATCHES/LOCKS/LINKAGES; ELECTRICAL SYSTEM. Outline of concern: On certain subject vehicles, it is possible the following concerns may happen when the connectivity service is available. 1. The hands-free capability does not work properly due to a communication error between CMU (Connectivity master unit) and the microphone. 2. The communication failure happens between the TCU (Telematics Communication Unit) and connectivity server due to improper software of the TCU. 3. Door lock operation will work even though the key fob is inside of the vehicle. Outline of repair: Reprogram TCU and C-BCM with modified software, using a specific MDRT3 tool.
SA-044-192019-10-30. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING. The "FORCED IGNITION ON PROCEDURE" was made available to dealers through this service alert.
SA-043-192019-10-30. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. On 7th generation vehicle (2019-2020 Mazda3 (BP) and 2020 CX-30 (DM)), when the door is opened/closed with the ignition switch off, the battery current is approximately 7A, which is three times larger than previous generation models (2.5A on Mazda6 (GL)). In addition, after the door is closed, a 6A current continues for 6 minutes on 7th generation vehicles. This is why frequent door operation in the show room may result in low battery voltage.To avoid a drained battery, especially when the vehicle is displayed for customers in a show room (with door operation being more frequent and battery consumption being larger), it is highly recommended to perform more frequent battery maintenance than for previous generation models.
09-036-19-36232019-10-30. Service bulletin. EXTERIOR LIGHTING. Some customers may complain about an instrument cluster warning message "Auto Light System Malfunction. Turn On/Off Lights Manually". DTC B10AD:09 (Humidity sensor/solar radiation sensor/auto light sensor/rain sensor malfunction) may also be stored with the exterior light warning indicator light ON.display. This is caused by the rain sensor detecting a temperature higher than the operation range and temporarily stopping the auto light system. As a fail-safe, the low beam headlights are turned on. The auto light system will start to operate normally when the A/C is turned on and the interior temperature drops. To correct this concern, the heat resistance performance of the rain sensor has been enhanced.
SA-042-192019-10-04. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM; EQUIPMENT ADAPTIVE/MOBILITY. Customers having MAZDA CONNECT concerns should have their vehicle repaired using the following repair procedure. NOTE: Before proceeding: Confirm that the Connectivity Master Unit (CMU) is updated to the latest software version. Go to MGSS - Infotainment - MAZDA CONNECT Updates, Confirm that the customers device is updated to the latest software version. Apple Carplay/Android Auto FAQ, go to SA-001/19.
MT-002-192019-10-04. Service bulletin. ENGINE AND ENGINE COOLING; ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:MANIFOLD/HEADER/MUFFLER/TAIL PIPE. If an engine assembly is replaced after a catastrophic internal mechanical failure, clean the intake manifold internally before installing a replacement engine assembly. If the intake manifold is not cleaned properly, the replacement engine may fail prematurely. Metallic debris from the old engine (with catastrophic internal mechanical failure) may rest inside the intake manifold. When the new engine assembly is installed, debris in the intake manifold will be ingested into the new engine and cause internal damage.

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.