DTC 13

DTC 13 Left (Bank 1) Oxygen Sensor Circuit Open:

Oxygen Sensor Circuit Wiring Diagram:

Circuit Description:

The Engine Control Module (ECM) supplies a voltage of about 0.45 volt between terminals "D6" and "D16". (If measured with a 10 megohm digital voltmeter, this may read as low as 0.35 volt.) The O2 sensor varies the voltage within a range of about 1 volt. If the left bank exhaust is rich, the oxygen sensor reading will be about 1.0 volt. If exhaust is lean the oxygen sensor reading will be about 0.10 volt. The sensor is like an open circuit and produces no voltage when it is below 316°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.

1. Code 13 will set:

- Engine at normal operating temperature.
- At least 2 minutes engine time after start.
- 02 signal voltage steady between 0.35 and 0.55 volt.
Throttle position sensor signal above 5% (about 0.3 volts above closed throttle).
- All conditions must be met for about 60 seconds. If the conditions for a DTC 13 exist the system will not go "Closed Loop".

2. This will determine if the sensor is at fault or the wiring or ECM is the cause of the DTC 13.

3. In doing this test use only a high impedance digital volt ohm meter. This test checks the continuity of CKTs 1665 and 351 because if CKT 351 is open the ECM voltage on CKT 1665 will be over 0.6 volt (600 mV).

Diagnostic Aids:

Normal "Scan" voltage varies between 100 mV to 999 mV (0.1 and 1.0 volt) while in "Closed Loop". If DTC 13 sets system will go into "Open Loop".
- Intermittent Malfunctions