Code 13: O2 Sensor (Heated Sensor Only) Open/Shorted Circuit: Notes

The ECM supplies a .45 volt signal between terminals D6 and D7. When oxygen sensor reaches operating temperature, it varies this voltage from approximately .1-.9 volt (lean to rich exhaust). Oxygen sensor does not produce voltage when temperature is less than 600°F (360°C) and engine operates in open loop.

1. Code 13 will set if all the following conditions are met for 40 seconds:
   • Engine temperature is greater than 157°F (69°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.

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

2. This determines if sensor, wiring or ECM is the cause of Code 13.
3. Use only a high impedance (10-megohm) digital volt/ohmmeter. This tests continuity of circuits No. 412 and 450. If circuit No. 450 is open, ECM voltage on circuit No. 412 will be greater than .6 volt.