GASKET 4N1868 - Caterpillar

System Operation Description:Periodic calibration of the oxygen sensor is required in order to ensure accurate readings and optimum engine performance. Refer to the Operation And Maintenance Manual for the maintenance interval schedule. The engine must be stopped and the sensor must be removed. The sensor must be placed in uncontaminated air in order to calibrate the sensor. The air must be free of exhaust.During the calibration, the Electronic Control Module (ECM) first establishes the reference for zero percent of oxygen by reading the sensor after the sensor has cooled for two minutes. The ECM energizes the heater in the sensor for five minutes. Last, the ECM reads the percent of oxygen in the surrounding air. The surrounding air is assumed to be clean with approximately 20.95 percent oxygen. The calibration offset and the calibration range are determined from these two points.Test Step 1. Check the Atmospheric Conditions
Determine the ambient temperature, relative humidity, and barometric pressure.
Use Table 1 to determine whether your relative humidity is within the permissible range for calibration of the oxygen sensor.
Find the row for your ambient temperature. If the temperature is less than 12 °C (54 °F), use the 12 °C (54 °F) row.If the temperature is more than 38 °C (100 °F), do not calibrate the sensor.
Find the column for your barometric pressure.
Find the relative humidity in the cell that intersects your column and your row. If your relative humidity is equal to the humidity or greater than the humidity that is listed in the Table, do not calibrate the sensor.If the humidity is 90 percent or more, do not calibrate the sensor.
Table 1
Ambient Temperature, Barometric Pressure, and Relative Humidity for Calibration of the Oxygen Sensor
Ambient Temperature Barometric Pressure
96 kPa (13.9 psi) 97 kPa (14.7 psi) 99 kPa (14.4 psi) 101 kPa (14.6 psi) 102 kPa (14.8 psi) 104 kPa (15 psi) 105 kPa (15.2 psi) 107 kPa (15.5 psi) 109 kPa (15.8 psi) 110 kPa (16 psi) 112 kPa (16.2 psi) 113 kPa (16.4 psi)
Relative Humidity
12 °C (54 °F) 90 90 90 90 90 90 90 90 90 90 90 90
14 °C (57 °F) 85 85 85 85 90 90 90 90 90 90 90 90
16 °C (61 °F) 75 75 75 75 80 80 80 80 85 85 85 85
18 °C (64 °F) 65 65 65 70 70 70 70 75 75 75 75 75
20 °C (68 °F) 60 60 60 60 60 65 65 65 65 65 65 70
22 °C (72 °F) 50 50 55 55 55 55 55 60 60 60 60 60
24 °C (75 °F) 45 45 45 50 50 50 50 50 50 55 55 55
26 °C (79 °F) 40 40 40 45 45 45 45 45 45 45 50 50
28 °C (82 °F) 35 35 40 40 40 40 40 40 40 40 45 45
30 °C (86 °F) 35 35 35 35 35 35 35 35 35 40 40 40
32 °C (90 °F)