# Service bulletin 18\-050\-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: 11031455
- Published by NHTSA: 2026\-04\-22
- Manufacturer's number: 18\-050\-26
- Manufacturer's date: 2026\-04\-18
- NHTSA component: POWER TRAIN; ENGINE

## NHTSA's summary

Flash: Powertrain Control Module \(PCM\) Updates Customers must experience a Malfunction Indicator Lamp \(MIL\) illumination and the vehicle must SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Codes \(DTCs\): ● P0300 \- Multiple Cylinder Misfire \- In Active or Stored status set during cold start catalyst heating. ● P0301 \- Cylinder 1 Misfire \- In Active or Stored status set during cold start catalyst heating. ● P0302 \- Cylinder 2 Misfire \- In Active or Stored status set during cold start catalyst heating. ● P0303 \- Cylinder 3 Misfire \- In Active or Stored status set during cold start catalyst heating. ● P0304 \- Cylinder 4 Misfire \- In Active or Stored status set during cold start catalyst heating. ● P0305 \- Cylinder 5 Misfire \- In Active or Stored status set during cold start catalyst heating. ● P0306 \- Cylinder 6 Misfire \- In Active or Stored status set during cold start catalyst heating. Customers may also comment on one or more of the following: ● Check engine illuminates when fueling the vehicle while the engine is running. ● Vehicle has a noticeable misfire. ● Vehicle idles rough. ● Engine noise. NOTE: Noise is heard coming from the valvetrain. In addition, the following software enhancement is available: ● Update to prevent customers from driving their vehicles while the Electric Park Brake \(EPB\) is engaged. Engine torque will be limited to prevent the Rear Drive Unit from being damaged. NOTE: Previously, the EPB would remain engaged without any torque limit which could lead to the Rear Drive Unit being damaged/broken. This bulletin involves reprogramming the PCM with the latest available software.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2026/MC-11031455-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2026/MC-11031455-9999.pdf)

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

## Components

Engine, Transmission and driveline

## Trouble codes named

P0300, P0301, P0302, P0303, P0304, P0305, P0306

## Vehicles listed

- 2021 JEEP GRAND CHEROKEE
- 2021 JEEP GRAND CHEROKEE L

## Recalls for the same vehicles and component

- [2022217](/recalls/tc/2022217.md), 2022-04-28: Engine
- [22V284000](/recalls/nhtsa/22V284000.md), 2022-04-28: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:GAS RECIRCULATION VALVE \(EGR VALVE\)

## 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 \(850RE Transmission Only\)
- [113528](/bulletins/11035187.md), 2026-07-23, Service bulletin: POWER TRAIN. SHAFT \- AXLE HALF
- [113529](/bulletins/11035186.md), 2026-07-23, Service bulletin: POWER TRAIN. SHAFT \- AXLE HALF
- [112639](/bulletins/11034912.md), 2026-07-08, Service bulletin: ENGINE. THROTTLE BODY – NONE
- [112640](/bulletins/11034911.md), 2026-07-08, Service bulletin: ENGINE. THROTTLE BODY – NONE
- [112842](/bulletins/11034335.md), 2026-07-02, Service bulletin: ENGINE. BOLT \- HEX FLANGE HEAD
- [S2623000023](/bulletins/11031337.md), 2026-04-15, Service bulletin: POWER TRAIN; ELECTRICAL SYSTEM. Power Liftgate Inoperative.
- [18\-044\-26](/bulletins/11030229.md), 2026-03-25, Service bulletin: ENGINE. Flash: Powertrain Control Module \(PCM\) Updates Customers must experience a Malfunction Indicator Lamp \(MIL\) illumination and the vehicle must SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Codes \(DTCs\): ● \*\*P0111\-00 \- Intake Air Temperature Sensor 1 Circuit Range Performance Bank 1. \(In Active or Stored status\) ● P0071\-00 \- Ambient Air Temperature Sensor Performance. \(In Active or Stored status\) ● P0072\-00 \- Ambient Air Temperature Sensor Circuit "A" Low. \(In Active or Stored status\) ● P0073\-00 \- Ambient Air Temperature Sensor Circuit "A" High. \(In Active or Stored status\) ● P0011\-00 \- Bank 1 Camshaft 1 Position Timing Over Advanced Or. \(In Active or Stored status\) ● P25E4\-00 \- B Camshaft Position \- Unable To Achieve Locked Position Bank 1. \(In Active or Stored status\) ● P05BD\-00 \- Stop\-Start Mode Switch Range/Performance. \(In Active or Stored status\) ● P0116\-00 \- Engine Coolant Temperature Sensor 1 Performance. \(In Active or Stored status\) ● P062B\-00 \- Internal Control Module Fuel Injector Control Performance. \(In Active or Stored status\) ● P0604\-00 \- Internal Control Module Random Access Memory Ram Error. \(In Active or Stored status\) ● P060C\-00 \- Internal Control Module Main Processor Performance. \(In Active or Stored status\)\*\* ● P018B\-00 \- Fuel Pressure Sensor "B" Circuit Range/performance. \*\*\(In Active or Stored status\)\*\* ● P1CEA\-00 \- Boost Side EVAP Purge System Performance. \*\*\(In Active or Stored status\)\*\* ● P06DD\-00 \- Engine Oil Pressure Control Circuit Performance/Stuck Off. \*\*\(In Active or Stored status\)\*\* ● P00C6\-00 \- Fuel Rail Pressure Too Low \- Engine Cranking. \*\*\(In Active or Stored status\)\*\* ● P0300\-00 \- Multiple Cylinder Misfire. \*\*\(In Active or Stored status\)\*\* Customers may also experience one or more of the following: ● \*\*Oil Level High Warning in the Instrument Panel Cluster \(IPC\).\*\* ● Fully Autonomous Parking Assist \(FAPA\) is not deactivated when accelerator pedal is pressed. ● Vehicle is not heating up fast enough at freezi
- [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.

JSON: [/v1/bulletins/11031455](/v1/bulletins/11031455)

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