Service bulletin 01-017-18-3518

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	10145243
Published by NHTSA	2018-10-09
Manufacturer's number	01-017-18-3518
Manufacturer's date	2018-09-14
NHTSA component	ENGINE

NHTSA's summary

Some customers may experience a check engine light on and DTC P0401:00 stored in memory without any drivability issues. P0401:00 - [PCM] EGR flow insufficient detected. This concern may be caused by the detection logic for the DTC is too sensitive. To eliminate this concern, the control logic of the PCM has been modified.

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

Engine

Trouble codes named

P0401

Vehicles listed
MAZDA CX-9	2016, 2017, 2018

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

Other bulletins for the same vehicles and component
SA-041-26	2026-07-03. 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-029-26	2026-05-05. 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-026-26	2026-05-05. Service bulletin. This Service Alert supersedes the previously issued M-Tip(s) listed below. The changes are noted in Red text. MT-002/19 09/30/19 and 12/19/19 DESCRIPTION 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. Clean the intake manifold internally to remove any debris from old engine before installing the new replacement engine assembly. If the intake manifold cannot be properly cleaned internally, replace it.
SA-014-26	2026-04-02. Service bulletin. This Service Alert supersedes the previously issued SA(s) and TSB(s) listed below: The changes are noted in Red. SA-035/24 05/31/24 DESCRIPTION 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 Alert is to inform you about the water pump sealing mechanism and the criteria if replacement is necessary or not. A mechanical seal (A) is used for the water pump. This mechanical seal can seal coolant (B) by sliding a mating ring (C) against a seal ring (D). When the sliding surface temperature of the mechanical seal is more than 248 °F (120 °C) while driving, a small amount of steam (E) is leaked and bleeds through the bleeding hole (F). After drying, the steam leaves a green coolant deposit near the water pump bleed hole (F). This is a normal condition and does not require water pump replacement. The water pump should only be replaced if there is an accumulation of crystallized coolant near the bleed hole. When you encounter a water pump with coolant seepage marks, decide to replace it or not based on the following criteria using sample photos. NOTE: During the initial period of use, the sliding surfaces of the seals may not yet be fully settled, which can temporarily increase the amount of leakage. Continued use will allow the surfaces to settle, reducing the leakage. Replacing parts that are already settled with new ones will increase the leakage again until the new parts become conditioned. Therefore, replacement should be avoided in this initial period of use. As a guideline, this applies to vehicles with less than 1,860 miles (3000 km) of mileage.
SA-052-25	2025-12-05. Service bulletin. 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.
CSP11a Warranty	2025-07-02. Warranty extension. Mazda Motor Corporation has decided to conduct a Customer Service Program (CSP11) to extend the limited powertrain warranty to 10 years or 120,000 miles, whichever occurs first, for necessary repairs if the covered vehicle has coolant leaks at the cylinder head, around the exhaust manifold. A dealer must inspect and confirm the covered vehicle is exhibiting coolant leaks at the cylinder head around the exhaust manifold matching Technical Service Bulletin 01-002/23 (Feb. 10, 2023) for the repair to be covered.
CSP11 Owner Letter	2025-01-04. Warranty extension. Dear Mazda Owner: You are receiving this notice because Mazda’s records indicate that your 2019-2020 CX-5, 2016-2020 CX-9, or 2018-2020 Mazda6 vehicle was equipped with a SKYACTIV-G 2.5T (Turbocharged) engine (“Covered Vehicle”). Mazda Motor Corporation has decided to conduct a Customer Service Program CSP (11) to inform you that Mazda is extending the limited powertrain warranty to provide necessary repairs free of charge if your Covered Vehicle has coolant leaks at the cylinder head around the exhaust manifold and to inform you that you may be eligible to receive reimbursement for past out-of-pocket expenses you previously incurred for such repairs on the terms and conditions as described below. Powertrain Warranty Extension: Mazda is extending the limited powertrain warranty to 10 years or 120,000-miles, whichever occurs first, to provide necessary repairs at no cost to you if your Covered Vehicle has coolant leaks at the cylinder head around the exhaust manifold. A dealer must inspect and confirm your Covered Vehicle is exhibiting coolant leaks at the cylinder head around the exhaust manifold matching Technical Service Bulletin 01-002/23 (Feb. 10, 2023) for you to receive the repairs at no cost to you.
CSP12	2024-12-04. Warranty extension. CUSTOMER SERVICE PROGRAM CSP12 - DENSO LOW-PRESSURE FUEL PUMP CUSTOMER SERVICE PROGRAM WARRANTY EXTENSION: Attention ALL Mazda Dealers: This is a Warranty Extension and not a recall campaign. Repairs are not to be made unless there is a confirmed low-pressure fuel pump failure within the coverage period. As of November 18, 2024 Repair Procedures and Parts and Warranty documents are available.
CSP12 Repair	2024-12-04. Warranty extension. CUSTOMER SERVICE PROGRAM CSP12 - DENSO LOW-PRESSURE FUEL PUMP CUSTOMER SERVICE PROGRAM WARRANTY EXTENSION: Attention ALL Mazda Dealers: This is a Warranty Extension and not a recall campaign. Repairs are not to be made unless there is a confirmed low-pressure fuel pump failure within the coverage period. As of November 18, 2024 Repair Procedures and Parts and Warranty documents are available.
CSP12 Repair MX5	2024-12-04. Warranty extension. CUSTOMER SERVICE PROGRAM CSP12 - DENSO LOW-PRESSURE FUEL PUMP CUSTOMER SERVICE PROGRAM WARRANTY EXTENSION: Attention ALL Mazda Dealers: This is a Warranty Extension and not a recall campaign. Repairs are not to be made unless there is a confirmed low-pressure fuel pump failure within the coverage period. As of November 18, 2024 Repair Procedures and Parts and Warranty documents are available.