CODE 13, HEATED OXYGEN (O2) SENSOR CKT, OPEN CKT (GSi): Notes

ECM supplies about .45 volt between ECM terminals D6 and D7. If voltage is measured with a 10-megohm DVOM, reading may be as low as .32 volt. The heater circuit of the O2 sensor is turned on when engine is running. The O2 sensor produces a varying voltage as engine reaches normal operating temperature. Voltage varies between .1-1.0 volt.

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

1. Code 13 sets if the following conditions are present for 60 seconds.
   • Engine temperature is greater than 158°F (70°C).
   • Engine has been running for at least 2 minutes.
   • O2 signal voltage is steady between .347-.547 volt.
   • Throttle angle is greater than 5 percent.

   If conditions for Code 13 exist, system will not go into closed loop.

2. This determines if O2 sensor, ECM and/or wiring is faulty.
3. Use only high impedance DVOM when performing this test. This checks continuity of terminals D6 and D7. If D6 is open, ECM voltage on D7 will be greater than .6 volt (600 mV).