Possible causes

– Fuel delivery system
– Engine Coolant Temperature (ECT) sensor or wiring connectors
– MAP sensor or wiring connectors
– O2 sensor wiring or connectors
– Engine mechanical system

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1129 JEEP Description

The Powertrain Control Module (PCM) detects a condition where the vehicle has remained in open loop fuel control ,from a start-up condition ,longer than a calibrated amount of time ,when conditions would have otherwise closed loop operation.

JEEP Technical Service Bulletins for P1129 code