DTC 13

DTC 13 - Oxygen Sensor (O2S) Circuit (Open Circuit):

Oxygen Sensor (O2S) Wiring Circuit:

Circuit Description:

The PCM supplies a voltage of about .45 volt between terminals "BD2" and "BD3". (If measured with a 10 megohm digital voltmeter, this may read as low as .32 volt.) The Oxygen Sensor (02S) varies the voltage within a range of about 1 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 Oxygen Sensor (O2S) circuit or cold Oxygen Sensor (O2S) causes "Open Loop" operation.

DTC 13 will set if:
^ Engine temperature above 43°C (110°F).
^ Engine run time more than 40 seconds.
^ O2S signal voltage is steady between .35 and .56 volt.
^ Throttle angle above 3%.
^ All conditions met for at least 30 seconds.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. If the conditions for a DTC 13 exist, the system will not go to "Closed Loop."
2. This will determine if the sensor or the wiring is the cause of the DTC 13.
3. In doing this test, use only a high impedance digital volt ohmmeter. This test checks the continuity of CKTs 412 and 413. If CKT 413 is open the PCM voltage on CKT 412 will be over .6 volt (600 mV).

Diagnostic Aids:

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.

Check for:

^ Poor Connection or Damaged Harness - Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.
^ Intermittent Test - With Tech 1, monitor O2S signal voltage while moving related connectors and wiring harness, with warm engine running at part throttle in "Closed Loop." If the failure is induced, the O2S signal voltage reading will change from its normal fluctuating voltage (above 600 mV and below 300 mV) to a fixed value around 450 mV. This may help to isolate the location of the malfunction.