DTC 13

Code 13 will set under the following conditions:

^ Engine at normal operating temperature
^ At least 2 minutes after engine start.
^ 02 signal voltage at terminal M2-23 of ECM steadily reading between 0.35 and 0.55 volts for more than one minute. The ECM supplies a voltage of about 0.5 volts between terminals M2-23 and M2-22. (If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volts).
^ The O2 sensor varies voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volts if exhaust is lean.
^ Throttle position sensor signal above 7 % (about 0.35 volts above closed throttle voltage.)
^ All conditions must be met for about 60 seconds.
^ The sensor acts like an open circuit and produces no voltage when the temperature is below 360°C (600°F). An open sensor circuit or cold sensor causes open loop operation.