DTC 13

Code 13 Diagnostic Chart:

Code 13 Circuit Diagram:

CIRCUIT DESCRIPTION:

The ECM supplies a voltage of about of 0.45 volt between terminals "3" and "20." (If measured with 10 Meg ohm digital voltmeter, this may read as low as 0.32 volts.) The O2 sensor varies the voltage within a range of about 1.0 volt, if the exhaust is rich, down through about .10 volt, if exhaust is lean. The sensor is like an open circuit and produces no voltage, when it is below 360°C (600°F). An open sensor circuit, or cold sensor, causes "Open Loop" operation.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart. Code 13 will set when the following conditions exist:

^ Engine at normal operating temperature.
^ At least 5 minutes engine run time after start at part throttle.
^ 02 signal voltage steady between 0.35 and 0.55 volts,
^ Throttle angle is at off-idle condition.
^ All conditions must be met for about 60 seconds. If the conditions for a Code 13 exist, the system will not go "Closed Loop."

1. This test determines if the 02 sensor is the problem, or, if the ECM and wiring are at fault.

DIAGNOSTIC AIDS:

"Scan" voltage varies between 100 millivolts to 999 millivolts (0.1 and 0.999 volt). Verify a clean, tight ground connection for CKT 413. Open CKT(s) 412 or 413 will result in a Code 13. If Code 13 is intermittent, refer to DIAGNOSIS BY SYMPTOM under TESTING PROCEDURES.