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Service bulletin TSB 21-2330

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 id10201637
Published by NHTSA2021-09-30
Manufacturer's numberTSB 21-2330
Manufacturer's date2021-09-24
NHTSA componentPOWER TRAIN

NHTSA's summary

Some 2020 Mustang GT350 - 2020-2021 Mustang Mach 1/Shelby GT500 vehicles may exhibit a rear differential fluid leak at the differential cooler line fittings. This may be due to a seal within the fittings. To correct the condition, follow the service procedure to replace both rear differential cooler line fittings.

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

Transmission and driveline

Vehicles listed
FORD MUSTANG2020, 2021

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

Recalls for the same vehicles and component
20257072025-12-18. Powertrain
22V3820002022-05-27. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)
20202032020-05-11. Powertrain
20V2630002020-05-08. ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; POWER TRAIN:AUTOMATIC TRANSMISSION:GEAR POSITION INDICATION (PRNDL)

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
TSB 26-22262026-05-14. Service bulletin. This bulletin supersedes 26-2046. Reason For Update: update the parts list to change the claim quantity of the C clutch friction plates (HL3Z-7B164-A), C clutch steel plates (HL3Z-7B442-F), D clutch steel plates (HL3Z-7B442-D), add the rear driveshaft flange CV joint-to-pinion flange cup bolts and retaining straps (LK4Z-4B496-B) for Transit, and update the parts description for the transfer case fluids applicable for each vehicle line. Some of the vehicles listed in the Model statement above may exhibit all of the following conditions: * Harsh engagement * Delayed engagement * Harsh shift * Delayed shift * Illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0751, P0752, P0756, P0757, P0761, P0762, P0766, P0767, P0771, P0772, P2700, P2701, P2702, P2703, P2704, P2705, P2707, P2708, P0729, P0731, P0732, P0733, P0734, P0735, P0736, P076F, P07D9, P07F6 and/or P07F7 stored in the powertrain control module (PCM) or transmission control module (TCM). This may be due to PCM software and/or axial movement of the CDF clutch cylinder (7H351) sleeve causing hydraulic circuit
SSM 547192026-04-10. Service bulletin. For 20212026 vehicles equipped with the 10R80 transmission, a new Transmission Clutch Circuit Leak Test has been introduced in the Ford Diagnosis and Repair System (FDRS). This test utilizes the pressure and vacuum transducer (PVT) when available. When referred to a specific clutch (A-F) test by a pinpoint test in Workshop Manual (WSM), Section 307-01 > Diagnosis and Testing, the Clutch Assembly tests have been updated with a hyperlink to the new Transmission Line Pressure Test - Pressure Vacuum Transducer (PVT) Is Available procedure in WSM, Section 307-01 > General Procedures. This procedure provides instructions to perform the FDRS Transmission Clutch Circuit Leak Test when applicable. The new test improves the accuracy of detecting leaks within transmission fluid circuits and replaces the previous air check method. The previous air check procedure has been shown to produce a high rate of false positives, which may lead to unnecessary repairs when no actual leak is present. Accordingly, the air check procedure is not to be used for diagnosing internal transmission hydraulic leaks or as justification
SSM 546742026-04-06. Service bulletin. For 2021-2026 vehicles equipped with the 10R80 transmission, a new Transmission Clutch Circuit Leak Test has been introduced in the Ford Diagnosis and Repair System (FDRS). This test utilizes the pressure and vacuum transducer (PVT) when available. The Workshop Manual (WSM) has been updated under Section 307-01 > Diagnosis and Testing to include this procedure. The new test improves the accuracy of detecting leaks within transmission fluid circuits and replaces the previous air check method.
TSB 26-21122026-03-23. Service bulletin. This bulletin supersedes TSB 26-2059. Reason For Update: To add missing labor operations. Some of the vehicles listed in the Model statement above may exhibit at least one of the following conditions: - No upshift past second gear - Unable to achieve third gear ratio - Illuminated malfunction indicator lamp (MIL) with DTCs P0757 and P2701 This may be due to a damaged one-way clutch (OWC).
TSB 26-20462026-02-17. Service bulletin. This bulletin supersedes TSB 25-2611. Reason For Update: Change the part number for the transmission fluid heat exchanger bolt (Expedition/Navigator) as well as change the claim/package quantities for HL3Z-7B442-F and HL3Z-7B164-C. Some of the vehicles listed in the Model statement above may exhibit at least one of the following conditions: * Harsh engagement * Delayed engagement * Harsh shift * Delayed shift * Illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0751, P0752, P0756, P0757, P0761, P0762, P0766, P0767, P0771, P0772, P2700, P2701, P2702, P2703, P2704, P2705, P2707, P2708, P0729, P0731, P0732, P0733, P0734, P0735, P0736, P076F, P07D9, P07F6 and/or P07F7 stored in the powertrain control module (PCM) or transmission control module (TCM). This may be due to PCM software and/or axial movement of the CDF clutch cylinder (7H351) sleeve causing hydraulic circuit leaks.
TSB 25-26112026-01-06. Service bulletin. This bulletin supersedes TSB 25-2474 for 3 Part List corrections. Some of the vehicles listed in the Model statement above may exhibit at least one of the following conditions: * Harsh engagement * Delayed engagement * Harsh shift * Delayed shift * Illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0751, P0752, P0756, P0757, P0761, P0762, P0766, P0767, P0771, P0772, P2700, P2701, P2702, P2703, P2704, P2705, P2707, P2708, P0729, P0731, P0732, P0733, P0734, P0735, P0736, P076F, P07D9, P07F6 and/or P07F7 stored in the powertrain control module (PCM) or transmission control module (TCM). This may be due to PCM software and/or axial movement of the CDF clutch cylinder (7H351) sleeve causing hydraulic circuit leaks. NOTE: If internal transmission service is required to address a concern detected with the CDF clutch cylinder following this article, technicians should carefully inspect and replace other transmission components and flush transmission fluid cooler only as necessary to confirm proper function. Add a new line to the repair order to document any additional repairs
SSM 543662025-11-19. Service bulletin. Some 2015-2021 Ford and Lincoln vehicles may exhibit an illuminated MIL with diagnostic trouble codes (DTCs) P0011, P0012, P0014, P0015, P0016, P0017, P0018, P0019, P0021, P0022, P0024 and/or P0025. Pinpoint test HK in the Powertrain Control and Emissions Diagnosis (PC/ED) or in Section 303-14 of the Workshop Manual (WSM) has been updated to address this concern.
TSB 25-24752025-11-04. Service bulletin. This bulletin supersedes TSB 25-2301. Reason for update: update the Part List Description. Some of the vehicles listed in the Model statement above may exhibit at least one of the following conditions: * Harsh engagement * Delayed engagement * Harsh shift * Delayed shift * Illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0751, P0752, P0756, P0757, P0761, P0762, P0766, P0767, P0771, P0772, P2700, P2701, P2702, P2703, P2704, P2705, P2707, P2708, P0729, P0731, P0732, P0733, P0734, P0735, P0736, P076F, P07D9, P07F6 and/or P07F7 stored in the powertrain control module (PCM) or transmission control module (TCM). This may be due to axial movement of the CDF clutch cylinder (7H351) sleeve causing hydraulic circuit leaks. NOTE: If internal transmission service is required to address a concern detected with the CDF clutch cylinder following this article, technicians should carefully inspect and replace other transmission components and flush transmission fluid cooler only as necessary as needed to ensure proper function. Add a new line to the repair order to document any additional
TSB 25-24742025-11-04. Service bulletin. This bulletin supersedes TSB 25-2429 for a labor operation correction. Some of the vehicles listed in the Model statement above may exhibit at least one of the following conditions: * Harsh engagement * Delayed engagement * Harsh shift * Delayed shift * Illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0751, P0752, P0756, P0757, P0761, P0762, P0766, P0767, P0771, P0772, P2700, P2701, P2702, P2703, P2704, P2705, P2707, P2708, P0729, P0731, P0732, P0733, P0734, P0735, P0736, P076F, P07D9, P07F6 and/or P07F7 stored in the powertrain control module (PCM) or transmission control module (TCM). This may be due to PCM software and/or axial movement of the CDF clutch cylinder (7H351) sleeve causing hydraulic circuit leaks. NOTE: If internal transmission service is required to address a concern detected with the CDF clutch cylinder following this article, technicians should carefully inspect and replace other transmission components and flush transmission fluid cooler only as necessary to confirm proper function. Add a new line to the repair order to document any additional rep
TSB 25-24292025-09-18. Service bulletin. This bulletin supersedes TSB 25-2300 to update the production fix date. Some of the vehicles listed in the Model statement above may exhibit at least one of the following conditions: * Harsh engagement * Delayed engagement * Harsh shift * Delayed shift * Illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0751, P0752, P0756, P0757, P0761, P0762, P0766, P0767, P0771, P0772, P2700, P2701, P2702, P2703, P2704, P2705, P2707, P2708, P0729, P0731, P0732, P0733, P0734, P0735, P0736, P076F, P07D9, P07F6 and/or P07F7 stored in the powertrain control module (PCM) or transmission control module (TCM). This may be due to PCM software and/or axial movement of the CDF clutch cylinder (7H351) sleeve causing hydraulic circuit leaks. NOTE: If internal transmission service is required to address a concern detected with the CDF clutch cylinder following this article, technicians should carefully inspect and replace other transmission components and flush transmission fluid cooler only as necessary to confirm proper function. Add a new line to the repair order to document any additional re