Code 13, Open Oxygen Sensor Circuit (Except 4.3L Turbo): Notes

When exhaust temperature is less than 600°F (316°C), the O2 sensor is open and produces no voltage. An open sensor circuit or cold sensor will not all system to entire closed loop.

1. Code 13 will set at normal operating temperature if at least 2 minutes have passed since engine start, Code 21 or 22 is not present, O2 signal voltage is steady at .35-.55 volt and throttle position sensor signal is greater than idle. All conditions must be met for at least 1 minute.
2. This determines if fault is in O2 sensor, ECM or wiring.
3. Use only a high-impedance Digital Volt-Ohmmeter (DVOM) while checking for continuity in signal and ground circuits. If ground circuit is open, voltage on signal circuit will be greater than .6 volt.