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Service bulletin 15-003-20-3737a

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)
TypeService bulletin
NHTSA id10182100
Published by NHTSA2020-11-03
Manufacturer's number15-003-20-3737a
Manufacturer's date2020-10-02
NHTSA componentSTEERING; FORWARD COLLISION AVOIDANCE; SERVICE BRAKES; ELECTRICAL SYSTEM; EQUIPMENT ADAPTIVE/MOBILITY

NHTSA's summary

Some vehicles may exhibit that the SBS/SCBS warning light (amber) turns ON right after the engine is started with DTC U0420:68 [FSC] (Error signal received from electric power steering (EPS) control module) stored in memory. For Mazda6 and CX-5, the following error messages may appear in the instrument cluster. • Front camera sensor system malfunction • Forward Smart City Brake Support Malfunction • Driver attention alert system malfunction. This may be caused by the battery voltage falling and the EPS control module failing the initial learning for the steering center position while cranking. The FSC detects the error notified by the EPS control module. To correct this concern, the control software of the EPS control module has been modified while the repair procedure modifies the FSC for earlier repairs in the market.

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

Brakes, Driver assistance, Electrical system, Equipment and accessories, Steering

Trouble codes named

U0420

Vehicles listed
MAZDA CX-92018, 2019, 2020
MAZDA MAZDA32017, 2018
MAZDA MAZDA62017, 2018, 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
23V4870002023-07-14. BACK OVER PREVENTION: SENSING SYSTEM: CAMERA
19V4030002019-05-30. ELECTRICAL SYSTEM:WIRING
20173122017-06-22. Brakes

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-041-26a2026-10-03. Service bulletin. DESCRIPTION If you encounter any type of electrical concern (e.g, dead battery, engine no start, DTC(s) stored...), interview the customer before proceeding with normal MGSS diagnosis by asking if any aftermarket devices have been installed. Aftermarket devices may be the cause of the electrical concern. Below are a few examples of unusual electrical concerns caused by aftermarket devices. Examples: 1. Devices connected to the DLC-2 (battery discharge/DTC stored) 2. Devices plugged into the 12V outlet 3. GPS tracking device (engine no start/battery discharge) 4. Dash cam (DTC stored) 5. Non-certified USB cable (Apple Carplay™/ Android Auto™ will not connect) 6. Over-sized wheels/tires (incorrect GPS location) 7. DTC C0023:14 8. Decorative trim and/or cover on the START/STOP ENGINE button
SA-041-262026-07-03. Service bulletin. This SA supersedes the previously issued SA(s) listed below. The changes are noted in Red. SA-061/25 12/17/25 DESCRIPTION If you encounter any type of electrical concern (e.g, dead battery, engine no start, DTC(s) stored...), interview the customer before proceeding with normal MGSS diagnosis by asking if any aftermarket devices have been installed. Aftermarket devices may be the cause of the electrical concern. Below are a few examples of unusual electrical concerns caused by aftermarket devices. Examples: 1. Devices connected to the DLC-2 (battery discharge/DTC stored) 2. Devices plugged into the 12V outlet 3. GPS tracking device (engine no start/battery discharge) 4. Dash cam (DTC stored) 5. Non-certified USB cable (Apple Carplay™/ Android Auto™ will not connect) 6. Over-sized wheels/tires (incorrect GPS location) 7. DTC C0023:14 8. Decorative trim and/or cover on the START/STOP ENGINE button Example 1: Some electrical devices connected to the DLC-2 connector by insurance or mobile phone companies may cause: Battery discharge. The device may disrupt the CAN system battery saver mode. • IDS/MMDS will not communicate with the vehicle due to poor DLC-2 connection. The aftermarket device may cause DLC-2 female terminals to spread open.
SA-027-26a2026-07-03. Service bulletin. This SA supersedes the previously issued bulletin(s) listed below. The changes are noted below in Red. SA-027/26 04/16/26 DESCRIPTION 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. REPAIR PROCEDURE 1. Perform appropriate repair to vehicle. If needed, use the Battery Diagnostics of the DCA-8000 to test the charging and starting systems by following the on-screen instructions for entering the appropriate information. Refer to the Mazda DCA-8000 Instruction Manual for more information.
09-019-262026-07-03. Service bulletin. This bulletin supersedes the previously issued bulletin(s) listed below. The changes are noted in Red. 09-012/21 12/13/21, 06/10/21 and 04/27/21 DESCRIPTION Some customers may experience all of following symptoms: The door lock/unlock operation will not work using the remote transmitter button. 1. The door lock/unlock operation will not work using the door lock/release touch sensor. 2. The engine will not start using the ignition switch. 3. The transmitter operates by itself. 4. The key battery drains faster than usual. 5. Symptoms 1-3: This may be caused when excess load is applied to the remote transmitter, deforming the electrical terminals and creating poor contact with the battery. To eliminate this concern, the structure in the remote transmitter has been modified to reduce the deformation of the electrical terminals. Symptom 4-5: This may be caused when excessive load is applied to the remote transmitter, creating a gap around the gasket where moisture enters and corrodes the circuit board which in turn drains the key battery faster than usual. To eliminate this concern, the thickness of the case wall on the gasket mounting surface has been increased and the bonding strength of the components has been improved to prevent deformation. REPAIR PROCEDURE • If the battery is bad or installed incorrectly, replace the battery and/or install it correctly. • If the remote power saving function is off and the battery is good and installed correctly, replace the defective remote transmitter with a modified one according to the instructions on MGSS (IMMOBILIZER SYSTEM-RELATED PARTS PROGRAMMING). NOTE: DO NOT replace other remote transmitter(s) for the vehicle if they not experiencing an issue.
SA-029-262026-05-05. Service bulletin. This Service Alert supersedes the previously issued SA listed below: The changes are noted in Red. SA-011/24 02/12/24, 06/06/24, 07/29/24 DESCRIPTION Mazda has developed factory recommended scheduled maintenance services that support all major vehicle systems. Mazda recommends dealers follow the scheduled maintenance tables as cited in the vehicle-specific workshop manual or owner's manual. Services performed outside of Mazda's factory scheduled maintenance are not recommended. These services are unnecessary and create unneeded expenses for your customers. SCHEDULED MAINTENANCE Refer to the applicable Workshop Manual or Owner's Manual for vehicle -specific manufacturer scheduled maintenance. Workshop Manual - Refer to section 00-00 SCHEDULED MAINTENANCE. Owner's Manual - Refer to section 8 Maintenance and Care. b. Note: Please refer to the information below outlining the services not included in Mazda's Factory Scheduled Maintenance: IMPORTANT: Recommending fluid flushes when not necessary can lead to customer confusion and dissatisfaction. Fluid flushing for preventive maintenance purposes is strongly discouraged, unless otherwise specified in a published procedure (Owner’s Manual, Workshop Manual, Technical Service Bulletin, etc.).
SA-027-262026-05-05. Service bulletin. This SA supersedes the previously issued bulletin(s) listed below. The changes are noted below in Red. SA-007/25 10/22/25, 06/02/25 and 02/03/25 DESCRIPTION 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. 2. CCA (Cold Cranking Amps): CCA ratings are normally located on a sticker affixed to the top of the battery to indicate a battery’s Cold Cranking Amps. CCA rated batteries are supplied with domestically produced vehicles. NOTE: If an incorrect CCA rating is entered into the Mazda DCA-8000, it will result in a false result and invalid Warranty Code from the tester. This will also result in unnecessary replacement of batteries. TEST PROCEDURE 1. Connect the charger clamps to the appropriate battery posts.
SA-021-262026-05-05. Service bulletin. This Service Alert supersedes the previously issued SAs and bulletin(s) listed below: The changes are noted below in red. SA-010/23 02/09/23 DESCRIPTION Some customers may experience one or more electrical malfunctions after a vehicle body repair. A newly painted fender stay (2) may be causing a poor front harness (1) ground connection. The front fender stay (2) newly painted surface at ground point (3), where attachment bolt (4) is seated, may create a poor front harness ground connection. NOTE: DO NOT paint ground point (3) attachment bolt (4) is seated. NEWLY INSTALLED FRONT FENDER STAY NOTE: CAUTION: If the bolt (4) contact area (3) is painted when the front fender stay (2) is newly replaced, it could cause a malfunction in the PCM. Before painting a newly replaced part, protect the bolt (4) contact area (3) with masking tape (5) as shown in the figure.
SA-061-252026-01-04. Service bulletin. If you encounter any type of electrical concern (e.g, dead battery, engine no start, DTC(s) stored...), interview the customer before proceeding with normal MGSS diagnosis by asking if any aftermarket devices have been installed. Aftermarket devices may be the cause of the electrical concern. Below are a few examples of unusual electrical concerns caused by aftermarket devices.
SA-055-252025-12-05. Service bulletin. 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-051-252025-12-05. Service bulletin. 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.