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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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By component

By trouble code

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Bulletins, newest first
01-003-25b2026-01-03. Service bulletin. ENGINE. Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. • Engine temperature gauge fluctuates. • Low coolant temperature indicator (blue) light stays on longer or turns on while driving. • Poor heater performance, especially at idle. • This concern may be caused if the coolant control valve fail-safe thermostat opens at a temperature lower than the normal temperature due to a deformation of the thermostat diaphragm. To eliminate the concern, the water flow control valve specification has been modified.
01-003-25a2026-01-03. Service bulletin. ENGINE. Some customers may experience a check engine light ON with DTC P0126:00 (Thermostat stuck open) and one or more of the following symptoms: Engine takes longer to warm up. Engine temperature gauge fluctuates. Low coolant temperature indicator (blue) light stays on longer or turns on while driving. Poor heater performance, especially at idle. This concern may be caused if the coolant control valve fail-safe thermostat opens at a temperature lower than the normal temperature due to a deformation of the thermostat diaphragm. To eliminate the concern, the water flow control valve specification has been modified.
SA-056-252025-12-05. Service bulletin. POWER TRAIN. When inspected, the differential or PTO oil is dark or black. This is considered normal and NO repair should be performed. During production, differential ring and pinion gears receive a manganese phosphate coating (commonly referred to as black oxide). This coating forms a porous, oil-retentive surface that improves boundary lubrication and reduces adhesive wear during initial contact cycles. Designed as a sacrificial layer, it is gradually removed under load throughout the break-in process. As a result, after the first few hundred miles, or at the initial gear oil service interval, the lubricant may appear darkened by the worn-off coating. It will contain trace ferrous particles from the normal run-in of the gear teeth and bearing surfaces. This condition is expected and does not, by itself, indicate an issue with the differential or PTO gears.
SA-055-252025-12-05. Service bulletin. SERVICE BRAKES. Some vehicles exhibit brake related concerns such as brake noise, brake judder or brake dragging. If you encounter a customer complaint for any one of these symptoms, refer to the following information to understand why symptoms may occur, and to better assist the customer in resolving their specific brake concern. NOTE: Before following this Service Alert repair procedure, ensure published TSBs in MGSS have been completed per model year.
SA-052-252025-12-05. Service bulletin. ENGINE; POWER TRAIN. 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. Examples of residue or seepage that may not be considered a leak and that may not require repair based on splash shield inspection.
SA-051-252025-12-05. Service bulletin. STEERING; SUSPENSION; POWER TRAIN; WHEELS. Noise, Vibration, and Harshness (NVH) Diagnostic Guidelines Diagnostic Guidelines When diagnosing NVH concerns, it is essential to first classify the issue into one of three primary categories: Noise, Vibration, or Harshness. Many customer complaints may involve overlapping symptoms, such as both noise and vibration, so identifying the dominant characteristic is critical. Once the primary symptom is determined, follow the appropriate diagnostic path. For example, if a concern includes both noise and vibration but is related to vehicle speed, the vibration diagnostic path should be followed. When considering component replacement during the diagnostic process, it is best practice to start with the lowest cost or most accessible part unless diagnostic evidence clearly identifies a more expensive or complex component as the root cause. This approach helps minimize repair costs and avoids unnecessary part replacements. For example, a growling or bearing whine noise may be mistakenly attributed to internal components in the differential, transfer unit, or transmission, when the actual source is a wheel bearing. Misdiagnosis like this can lead to unnecessary repairs, added time and cost. To help prevent this, always follow the guidelines in the repair procedure.
SA-020-25a2025-12-05. Service bulletin. WHEELS. There have been warranty claims submitted for growling or bearing whine noise in differentials, transfer units and transmissions where the source of the noise was a wheel bearing. This misdiagnosis can lead to multiple repair attempts, warranty debits, and additional inconvenience and/or cost to the customer. To reduce the chance of this occurring, please follow the steps outlined in the repair procedure.
09-042-252025-12-04. Service bulletin. UNKNOWN OR OTHER; STRUCTURE:BODY. Some customers may experience that after the doors are locked and the Fuel Door Lock Delay with MAZDA CONNECT has passed (default setting is 90 seconds), the fuel-filler lid does not lock, but can be opened when pressed. NOTE: The fuel-filler lid does not lock immediately after the doors are locked, but after the time set in the Fuel Door Lock Delay (0, 30, 60, 90, and 120 seconds). Although the root cause has not been identified, the vehicle should be repaired by adjusting the fuel-filler lid opener cable position when there is a customer complaint.
SA-047-252025-11-05. Service bulletin. ELECTRICAL SYSTEM; UNKNOWN OR OTHER. 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.
SA-044-252025-11-05. Service bulletin. ELECTRICAL SYSTEM. For improvement of electrical diagnosis, the SKYACTIV® Wiring Terminal Test Kits has been delivered all the dealers. The terminal test kit enables you: To check pin fit drag of all PCM terminals used in SKYACTIV® vehicles and compare suspect terminal drag with a known good terminal. To measure the voltage/resistance avoiding any terminal damage.
SA-012-25c2025-11-05. Service bulletin. UNKNOWN OR OTHER. Customers having MAZDA CONNECT concerns should have their vehicle repaired using the following repair procedure.
SA-011-25a2025-11-05. Service bulletin. STRUCTURE:BODY. Some customers will report that their fuel door (AKA, fuel filler door, fuel lid, and fuel-filler lid) was stuck closed and would not open to refuel the vehicle. Follow the repair steps below unless the conditions outlined in TSB 09-007/25 - FUEL-FILLER LID PANEL IS DEFORMED for 2019-2025 Mazda3 and 2020-2025 CX-30 are present.
SA-007-25b2025-11-05. Service bulletin. ELECTRICAL SYSTEM. The Mazda DCA-8000 is required for all warranty battery testing. If the Mazda DCA-8000 is not used, incorrect battery testing may result in unnecessary battery replacement. Use the following test procedures in this Service Bulletin to test Mazda vehicle batteries and to generate a Warranty Code. NOTE: A Warranty Code is required for warranty claim submission Battery Identification (Mazda batteries have 2 rating types) 1. JIS (Japanese Industrial Standard): JIS codes are six-digit alpha-numeric markings (excluding i-STOP batteries e.g. Q-85, S-95) molded into the top of the battery to identify a battery by the capacity (amps), dimensions, and battery terminal type. Vehicles manufactured in Japan come from the factory with a JIS rated battery. NOTE: Replacement batteries may use a CCA rating. If so, use the CCA rating listed on the battery.
09-040-252025-11-05. Service bulletin. UNKNOWN OR OTHER; ELECTRICAL SYSTEM. Some customers may experience rear subwoofer audio sound pauses intermittently at high volume levels. When the volume level is lowered, the subwoofer audio sound resumes. The actual volume level may vary depending on the audio source. If the audio source consists of many low frequency (40 - 70 Hz) sounds, the concern may occur at volume level 35 or higher. This concern may be caused by improper audio amplifier control software. To eliminate this concern, the control software has been modified.
09-034-25a2025-11-05. Service bulletin. STRUCTURE:BODY. Some customers may notice water in the trunk after a car wash or heavy rain. This may be caused by insufficient sealing performance of the trunk lid weatherstrip. Due to improper installation of weatherstrips, the lip of the weatherstrip may lean toward the inside of the trunk, resulting in insufficient sealing performance. To eliminate this concern, the length of the trunk lid weatherstrip has been extended 14 mm {0.5 in.}.
SA-043-252025-10-03. Service bulletin. UNKNOWN OR OTHER. Some vehicles may have one of the following DTCs stored in memory along with a system status notice on the Multi-information display OR display a system status notice with no DTC: C1001:92 - Forward sensing camera (FSC) poor field of view [Gen 6 vehicles] B14F0:92 - General temporary failure in forward sensing camera (FSC) [Gen 7 vehicles built on or before March 2, 2019] No DTC - Warning Message only [Gen 7 vehicles built after March 2, 2019] DTC C1001:92 or B14F0:92 set as a past record for low visibility of the Forward Sensing Camera (FSC). It does not mean there is an actual FSC defect. In some cases the customer may have a concern with the Lane Departure Warning System (LDWS) and/or High Beam Control system (HBC). In other cases this DTC might be found without a related customer concern.
SA-042-252025-10-03. Service bulletin. UNKNOWN OR OTHER. Interior parts made of resin have antistatic coating to prevent dust from sticking on the surfaces, and depending on the conditions of use, the antistatic components may crystallize slightly, giving an appearance of white stains on the surface.
SA-017-25c2025-10-03. Service bulletin. UNKNOWN OR OTHER; ELECTRICAL SYSTEM. Mazda Connected Services - Frequently Asked Questions
SA-039/252025-09-05. Service bulletin. UNKNOWN OR OTHER; STRUCTURE:BODY. Some vehicles may experience exterior trim heat damage such (melted, separating, etc.) when parked near a glass building or Low-E windows. This may be caused by the sun's reflection. If a structure's windows create enough of a curve, the concave glass can focus the sun's rays onto a small area and acting like magnifiying glass direct the sunbeams into a hot pinpoint of light. This magnifcation of the sun's rays can cause damage to vehicle trim (see examples). Additional information and exemplar images regarding this phenomenon can be found by performing a google search.
SA-038-252025-09-05. Service bulletin. UNKNOWN OR OTHER. When replacing the MAZDA CONNECT remote tuner (RT) with a replacement tuner for any reason, a call must be made to inform SiriusXM of the existing Radio ID and the new/replacement SAT Radio ID as soon as possible to ensure the customer leaves the dealership with an active SAT radio.
SA-035-252025-09-04. Service bulletin. ELECTRICAL SYSTEM; UNKNOWN OR OTHER. Some vehicles may show “TSR system performance is reduced. Navigation Data Unavailable" or "Check Navigation SD Card" in the meter while driving.
SA-023-25b2025-09-04. Service bulletin. UNKNOWN OR OTHER; ENGINE; ELECTRICAL SYSTEM; EXTERIOR LIGHTING. Some customers may complain about any of the following: 1. Infotainment Center Display does not provide the Authorization Code (OTP) during the MyMazda App Connected Vehicle enrollment. 2. Remote function(s) inoperative. Engine Start / Stop Door Lock / Unlock Lights ON / OFF Climate Control 3. MAZDA CONNECT connected vehicle reception strength icon shows "X" or " ".
SA-012-25b2025-09-04. Service bulletin. UNKNOWN OR OTHER; ELECTRICAL SYSTEM. Customers having MAZDA CONNECT concerns should have their vehicle repaired using the following repair procedure.
SA-009-25a2025-09-04. Service bulletin. ELECTRICAL SYSTEM; UNKNOWN OR OTHER. Some customers may experience a Connected Vehicle failure. The MyMazda App may display an Error Code. This document provides Error Code description and recovery information to assist with repairs.
09-034-252025-09-04. Service bulletin. UNKNOWN OR OTHER; STRUCTURE:BODY. Some customers may notice water in the trunk after a car wash or heavy rain. This may be caused by insufficient sealing performance of the trunk lid weatherstrip. Due to improper installation of weatherstrips, the lip of the weatherstrip may lean toward the inside of the trunk, resulting in insufficient sealing performance.

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