# Service bulletin 21B26\-S1

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.

- Type: Service bulletin
- NHTSA id: 10198613
- Published by NHTSA: 2021\-07\-01
- Manufacturer's number: 21B26\-S1
- Manufacturer's date: 2021\-06\-08
- NHTSA component: ENGINE AND ENGINE COOLING

## NHTSA's summary

In some of the affected vehicles, the engine's secondary timing chain tensioner may not have been properly activated during assembly, which could result in a timing loss. Timing loss could lead to internal engine damage, a rough running engine , and engine misfires.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2021/MC-10198613-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2021/MC-10198613-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Engine

## Vehicles listed

- 2020 FORD MUSTANG

## Other bulletins for the same vehicles and component

- [SSM 52542](/bulletins/11000294.md), 2024-05-23, Service bulletin: ENGINE. Some 2020\-2022 Mustang GT500 vehicles may exhibit a lack of power and/or an illuminated malfunction indicator lamp \(MIL\) with diagnostic trouble code \(DTC\) P1228. This may be due to the one\-way clutch on the supercharger drive assembly. With the supercharger belt removed, a failed one\-way clutch within the pulley rotates freely in both directions. The supercharger drive assembly KR3Z\-6J022\-B is now available as a lower level service part, separate from the supercharger assembly. Refer to the parts catalog and Workshop Manual \(WSM\), Section 303\-12 for installation.
- [SSM 52502](/bulletins/11000181.md), 2024-05-17, Service bulletin: ENGINE. Some 2020\-2022 Mustang GT500 vehicles may exhibit a lack of power and/or an illuminated malfunction indicator lamp \(MIL\) with diagnostic trouble code \(DTC\) P1228. This may be due to the one\-way clutch on the supercharger drive assembly. With the supercharger belt removed, a failed one\-way clutch within the pulley rotates freely in both directions. The supercharger drive assembly KR3Z\-6J022\-B is now available as a lower level service part, separate from the supercharger assembly. Refer to the parts catalog and Workshop Manual \(WSM\), Section 303\-12D for installation.
- [SSM 52335](/bulletins/10251952.md), 2024-03-20, Service bulletin: ENGINE AND ENGINE COOLING. For 2015\-2024 Ford and Lincoln vehicles equipped with turbocharged engines and customer concern of an engine oil leak, refer to Workshop Manual \(WSM\), Section 303\-00 for oil leak inspection and testing methods. Ford has evaluated turbochargers replaced for oil leak symptoms and although oil may collect on the external surface of a turbocharger, it is extremely rare for a turbocharger assembly to be the root cause of the oil leak. Careful inspection of the turbocharger oil feed and drain tubes should be performed along with the recommended WSM procedures as needed. Warranty claims for turbocharger replacement going forward will be assessed.
- [SSM 52334](/bulletins/10251951.md), 2024-03-20, Service bulletin: ENGINE AND ENGINE COOLING. Some 2011\-2024 Mustang and F\-150 vehicles equipped with a 5.0L engine may exhibit a tick tap and/or typewriter ticking noise at idle after an engine oil change. It is often referred to as typewriter noise because of its similarity to the sound of a mechanical typewriter. The noise in question may be heard on some engines when engine temperatures reach 150°F \(65°C\) or higher and engine speed is at idle up to approximately 1700 RPM. It can typically be heard at the front wheel well and is often isolated to the transmission bell housing or oil pan area. The typewriter noise tick rate can be faster or slower and is not detrimental to the engine function or durability and has no short or long term effects on the engine. This an operating characteristic of the 5.0L engine and no repairs should be attempted. This information along with an example audio clip has been added to the WSM Section 303\-00 Engine System General Information \> Diagnosis and Testing \> Engine \> PPT F \> Step F2.
- [TSB 23\-2132](/bulletins/10236033.md), 2023-05-31, Service bulletin: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM. Some 2018\-2023 Mustang vehicles \(non\-Shelby GT\-350\) may exhibit various concerns with the active exhaust system. These may include Exhaust Mode Selection Not Available messages, and/or illuminated malfunction indicator lamp \(MIL\) with diagnostics trouble codes \(DTCs\) P26C5, P26C6, P26FE, P2BF9, P2BFB, P26C7, P2BF5, P2BF8, P2BFD and/or P2BFA. This may be due to an improperly seated exhaust system. To correct the condition, follow the Service Procedure to diagnose the tailpipe actuator.
- [TSB 22\-2282](/bulletins/10225443.md), 2022-10-31, Service bulletin: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM. Some 2018\-2022 Mustang vehicles \(non\-Shelby GT\-350\) may exhibit various concerns with the active exhaust system. These may include Drive Mode Not Available or Exhaust Mode Not Available messages, and/or illuminated malfunction indicator lamp \(MIL\) with diagnostics trouble codes \(DTCs\) P26C5, P26C6, P26FE, P2BF9, P2BFB, P26C7, P2BF5, P2BF8, P2BFD and/or P2BFA. This may be due to an improperly seated exhaust system. To correct the condition, follow the Service Procedure to diagnose the tailpipe actuator .
- [TSB 22\-2140](/bulletins/10210472.md), 2022-04-26, Service bulletin: ENGINE AND ENGINE COOLING; EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY. Some 2015\-2020 Mustang Shelby GT350/GT350R vehicles may exhibit a hesitation or surge in the vehicle with no diagnostic trouble codes \(DTCs\) present. This may be accompanied by an inoperative cruise control system. This may be due to a transmission output shaft flange nut that has come loose, allowing the output shaft tone ring to move in relation to the output shaft causing an erroneous signal. To resolve the condition, follow the Service Procedure steps to replace the output shaft flange nut.
- [SSM 50578](/bulletins/10209027.md), 2022-03-15, Service bulletin: EQUIPMENT; ENGINE AND ENGINE COOLING; EQUIPMENT ADAPTIVE/MOBILITY. Some 2020\-2021 Mustang GT500 vehicles may exhibit a lack of power and/or an illuminated malfunction indicator lamp \(MIL\) with diagnostic trouble code \(DTC\) P1228. This may be due to the one\-way clutch on the supercharger drive assembly. With the supercharger belt removed, a failed one\-way clutch within the pulley rotates freely in both directions. The supercharger drive assembly KR3Z\-6J022\-B is now available as a lower level service part, separate from the supercharger assembly. Refer to the parts catalog and Workshop Manual \(WSM\), Section 303\-12D for installation.
- [TSB 21\-2390](/bulletins/10203650.md), 2021-12-02, Service bulletin: POWER TRAIN; ENGINE AND ENGINE COOLING. Some 2020\-2021 Mustang GT500 vehicles built on or before 30\-June\-2021 may exhibit a no crank/no start with no powertrain control module \(PCM\) communication condition if the oil level is approximately 1 or more quarts low and the oil life is at or less than 20%. This may be due to various parameters within the PCM. To correct the condition, follow the Service Procedure to reset and reprogram the PCM.
- [SSM 50103](/bulletins/10201586.md), 2021-09-28, Service bulletin: POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE \(TCM/PCM/TECM\); ENGINE AND ENGINE COOLING. Some 2020 Mustang vehicles equipped with a 5.0L engine built on 01\-Sep\-2020 and through 01\-Dec\-2020 may experience an illuminated malfunction indicator lamp \(MIL\) with diagnostic trouble code \(DTC\) P0369 in the powertrain control module \(PCM\). This may be due to a flatness concern on the mega cap on the right hand cylinder head. To correct the condition, replace the right\-hand cylinder head. Refer to Workshop Manual \(WSM\), Section 303\-01B \> Removal and installation \> Cylinder Head RH. For claiming, use causal part 6049 and applicable labor times in Section 06 of the Service Labor Time Standards \(SLTS\) Manual.

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