# Service bulletin 21\-009\-26

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: 11027640
- Published by NHTSA: 2026\-01\-14
- Manufacturer's number: 21\-009\-26
- Manufacturer's date: 2026\-01\-10
- NHTSA component: POWER TRAIN

## NHTSA's summary

Flash: Transmission Control Module \(TCM\) Updates \*Customers must experience a Malfunction Indicator Lamp \(MIL\) illumination and the vehicle may exhibit/set one or more of the following Diagnostic Trouble Codes \(DTCs\):\*\* ● P0979\-00 \- Shift Solenoid 3 Control Circuit Low. ● P0219\-00 \- Engine Overspeed Condition. ● P0731\-00 \- Gear 1 Shift Incorrect Ratio. \*\*Customers may experience the following: ● Shift shudder and shift shock during wide open throttle, high clutch energy shift.\*\* The following software update is also included: ● Improved high RPM in coasting situations for the 1\-2 shift This bulletin involves reprogramming the TCM with the latest available software.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2026/MC-11027640-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2026/MC-11027640-9999.pdf)

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

## Components

Transmission and driveline

## Trouble codes named

P0219, P0731, P0979

## Vehicles listed

- 2018 JEEP GRAND CHEROKEE

## Recalls for the same vehicles and component

- [2018422](/recalls/tc/2018422.md), 2018-08-09: Powertrain
- [2018223](/recalls/tc/2018223.md), 2018-05-01: Powertrain
- [18V280000](/recalls/nhtsa/18V280000.md), 2018-05-01: POWER TRAIN:AUTOMATIC TRANSMISSION

## Other bulletins for the same vehicles and component

- [S2621000004](/bulletins/11038329.md), 2026-10-07, Service bulletin: POWER TRAIN. The Customer May Complain About a Popping Noise, Grinding Noise, or an Intermittent No Reverse or Forward Transmission Engagement. The Tech May Find Damaged and/or Worn Transmission Output Shaft Splines \(850RE Transmission Only\)
- [S2623000023](/bulletins/11031337.md), 2026-04-15, Service bulletin: POWER TRAIN; ELECTRICAL SYSTEM. Power Liftgate Inoperative.
- [S2621000003 REV.A](/bulletins/11030138.md), 2026-03-18, Service bulletin: POWER TRAIN. The vehicle will exhibit a service transmission/check engine warning indicator for the following transmission models: 845RE, 8HP45, 850RE, 8HP50, 8HP70, 8HP75, 8HP75\-PHEV, 8HP75\-LCV, 8HP90, 8HP95. Transmissions may exhibit the following diagnostic codes: P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
- [S2621000003](/bulletins/11029770.md), 2026-03-05, Service bulletin: POWER TRAIN. Service transmission/check engine warning indicator for the 850RE, 8HP50, 8HP70, 8HP75, 8HP75\-PHEV transmissions that have fault codes P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
- [18\-001\-26](/bulletins/11027729.md), 2026-01-21, Service bulletin: POWER TRAIN. Flash: Powertrain Control Module \(PCM\) Updates Customers must experience a Malfunction Indicator Lamp \(MIL\) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes \(DTCs\): ● P0420 \- Catalyst System Efficiency Below Threshold Bank 1. ● P0430 \- Catalyst System Efficiency Below Threshold Bank 2. Customers may also experience the following: ● Catalyst damage and restricted exhaust flow, resulting in a reduction of engine power. This bulletin involves reprogramming the PCM with the latest available software.
- [9100534 Rev 1](/bulletins/11018452.md), 2025-05-19, Service bulletin: POWER TRAIN. Transmission "Transmission For transmission concerns related to DTCs P0733\-00, P1DA8\-00, and/or P1D92\-00, a repair is available, and transmission replacement is NOT required. Please reference TSB 21\-009\-25 Rev. A, for details on D\-clutch replacement. Please also note, visible ""glitter"" or debris in the pan and fluid color/condition/odor is NOT an indicator of transmission health and should not be used as the reason for unit replacement. Complete unit replacements instead of repairs for these DTCs may be subject to chargeback."
- [9100534](/bulletins/11016061.md), 2025-03-28, Service bulletin: POWER TRAIN. "Transmission For transmission concerns related to DTCs P0733\-00, P1DA8\-00, and/or P1D92\-00, a repair is available, and transmission replacement is NOT required. Please reference TSB 21\-009\-25 Rev. A, for details on D\-clutch replacement. Please also note, fluid color/condition/odor is NOT an indicator of transmission health and should not be used as the reason for unit replacement. Complete unit replacements instead of repairs for these DTCs may be subject to chargeback."
- [101232](/bulletins/11010205.md), 2024-11-07, Service bulletin: POWER TRAIN. Plate \- Planetary
- [S2309000013](/bulletins/10248877.md), 2024-01-16, Service bulletin: POWER TRAIN. Verifying Camshaft Diagnosis
- [S2221000003](/bulletins/10248562.md), 2024-01-08, Service bulletin: POWER TRAIN. 8\-Speed Transmission, Additional Transmission Fluid Leak Inspection/Repair Guidelines.

JSON: [/v1/bulletins/11027640](/v1/bulletins/11027640)

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