NGC

P1128-CLOSED LOOP FUELING NOT ACHIEVED - BANK 1

For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
With engine run time and coolant temperature above a calibrated value.

- Set Condition:
The 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 expected closed loop operation. Two Trip Fault. Three good trips to turn off the MIL





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE
Diagnose and repair any other active component or circuit DTCs before continuing with this procedure.
Turn the ignition on.
With the scan tool, select View DTCs. Copy DTC and Freeze Frame information.
Start the engine and allow it to reach operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

NOTE: Attempt to operate the vehicle under conditions similar to which the DTC was set.

NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.

With a scan tool, select View DTCs.
Is the DTC Active at this time?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking For An Intermittent DTC

2. CHECKING THE FUEL DELIVERY SYSTEM
Perform the diagnostic procedure for *CHECKING THE FUEL DELIVERY SYSTEM. Checking the Fuel Delivery System
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 3

3. CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION
Perform the diagnostic procedure for *CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION. Checking the Engine Coolant Temperature Sensor Operation

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 4

4. CHECKING THE MAP SENSOR OPERATION
Perform the diagnostic procedure for *CHECKING THE MAP SENSOR OPERATION. Checking the MAP Sensor Operation
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 5

5. CHECKING THE OXYGEN SENSOR OPERATION
Perform the diagnostic procedure for *CHECKING THE OXYGEN SENSOR OPERATION. Checking the Oxygen Sensor Operation
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 6

6. CHECKING THE ENGINE MECHANICAL SYSTEM
Perform the diagnostic procedure for *CHECKING THE ENGINE MECHANICAL SYSTEM. Checking the Engine Mechanical System

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 7

7. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors relative to the components tested in this procedure.
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to the components tested in this procedure and wiggle test the wiring and connectors.
Look for the data to change or for a DTC to set during the wiggle test.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Replace and program the PCM.
- Perform the PCM Verification Test. Powertrain Verification Test