P1128-CLOSED LOOP FUELING NOT ACHIEVED - BANK 1

For a complete wiring diagram Refer to Section 8W.


  • 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


Possible Causes
  
INTERMITTENT DTC
  
FUEL DELIVERY SYSTEM
  
ECT SENSOR, WIRING, OR CONNECTORS
  
MAP SENSOR, WIRING, OR CONNECTORS
  
O2 SENSOR, WIRING, OR CONNECTORS
  
ENGINE MECHANICAL SYSTEM
  
POWERTRAIN CONTROL MODULE (PCM)
  

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).



Diagnostic Test

1.DTC IS ACTIVE





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.




Is the status Active for this DTC?

Yes
  • Go to 2


No

2.CHECKING THE FUEL DELIVERY SYSTEM



Were any problems found?

Yes


No
  • Go to 3

3.CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION



Were any problems found?

Yes


No
  • Go to 4

4.CHECKING THE MAP SENSOR OPERATION



Were any problems found?

Yes


No
  • Go to 5

5.CHECKING THE OXYGEN SENSOR OPERATION



Were any problems found?

Yes


No
  • Go to 6

6.CHECKING THE ENGINE MECHANICAL SYSTEM



Were any problems found?

Yes


No
  • Go to 7

7.POWERTRAIN CONTROL MODULE (PCM)








Were any problems found?

Yes


No