Code 25, Oxygen Sensor Circuit, Lean Exhaust Indicated: Notes

ECM supplies approximately .45 volt between ECM terminals OX+ and OX1. If voltage is measured 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 between.1-.9 volt.

The O2 sensor will not produce voltage until sensor reaches 600°F (316°C). When sensor is less than normal operating temperature, an open loop condition exists.

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

Code 25 sets when O2 sensor signal voltage on Black wire remains below .2 volt for one minute or more with system in closed loop.