JEEP

18-001-26

Manufacturer communications

Publication date: 2026-01-14
Received by NHTSA: 2026-01-21
NHTSA record numbers: 11027729

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 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.

NHTSA manufacturer communications ↗

Reported code forms

P0420 P0430

Manufacturer wording

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

JeepP0420

Catalyst System Efficiency Below Threshold Bank 1

NHTSA 10243231 · NHTSA 11015523 · NHTSA 11020109

JeepP0430

Catalyst System Efficiency Below Threshold Bank 2

NHTSA 10243231 · NHTSA 11020110 · NHTSA 11027729

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Make	Model	Model year
Jeep	GRAND CHEROKEE	2018

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