Code 25, Oxygen Sensor Circuit Lean Exhaust Indicated: Notes

The ECM supplies approximately .45 volt between ECM terminals "OX" and "E1". If reading is taken with a 10-megohm DVOM, reading may be as low as .32 volt. The O2 sensor produces a varying voltage as engine reaches normal operating temperature. Voltage will vary from .10-.90 volt. The O2 sensor does not produce a voltage until sensor reaches 600°F (316°C). When sensor is less than this temperature, an "Open Loop" condition exists.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Code 25 will set when O2 sensor signal voltage on Black wire remains below .2 volt for one minute or more with system in "Closed Loop".