4.3L Turbo

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, O2 signal voltage is steady between .35-.55 volt and throttle position sensor signal is above idle. All conditions must be met for at least 1 minute.
2. This checks the oxygen sensor heating element. Resistance should be 3.5-14 ohms at 662°F (350°C).
3. This determines if fault is in O2 sensor, ECM or wiring.
4. 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.
5. If the A/C fuse is blown, check the A/C control circuit or generator for short circuits.