Code 13, Oxygen Sensor Circuit (Non-Heated O2 Sensor Only) Open Or Grounded Circuit: Notes

The ECM supplies approximately .45 volt between ECM terminals D7 and D6. 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 varies from .10-1.0 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.

1. Code 13 sets if:
   • Engine temperature is greater than 600°F (316°C).
   • Engine has been running for at least 50 seconds after start.
   • O2 signal voltage steady between 0-.347 volt or steady above .547 volt.
   • Throttle angle greater than 5 percent.
   • All the above conditions must be met for about 40 seconds.

     If the condition for a Code 13 exists, the system will not go into Closed Loop.

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