CORE AS-AFTERCOOLER 2851980 - Caterpillar

Which Generate This Code: The results of the oxygen calibration were out of tolerance. One of the following conditions has occurred:
The oxygen calibration was performed while the oxygen sensor was installed in the exhaust stack.
The oxygen calibration was performed while the oxygen sensor was in contaminated air.
The oxygen relay is intermittently energizing and de-energizing.
The oxygen buffer has failed.
The oxygen sensor has failed.
The ECM has failed.System Response:The oxygen calibration will be terminated. No changes will be made to the existing calibration values.The diagnostic code may be viewed on the Digital Diagnostic Tool (DDT), on the Engine Control Module (ECM), or on the Caterpillar Electronic Technician (Cat ET).Engine performance and emissions will be affected if an oxygen calibration that is required is not accomplished.Test Step 1. Perform the following diagnostic procedure: Oxygen Sensor SignalResults:
OK - STOP