P1128 JEEP – Closed Loop Fueling Not Achieved Bank 1

P1128 JEEP Possible Causes

• Manifold Absolute Pressure (MAP) sensor or wiring connectors
• O2 sensor wiring or connectors
• Engine mechanical system
• Faulty Powertrain Control Module (PCM)

How to Fix JEEP P1128 Code?

Start by checking the “Possible Causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

• Check Engine Light on (or Service Engine Soon warning light)

P1128 JEEP Meaning

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 duration, when conditions would otherwise have closed loop operation.