Home18-050-26 · JEEP
JEEP

18-050-26

Manufacturer communications

Publication date
2026-04-18
Received by NHTSA
2026-04-22
NHTSA record numbers
11031455

Manufacturer summary

Original wording in English

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.

NHTSA manufacturer communications ↗

Reported code forms

Manufacturer wording

Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.

Check vehicle applicability

A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.

MakeModelModel year
JeepGRAND CHEROKEE2021
JeepGRAND CHEROKEE L2021

Data coverage →