DTC 13

Code Chart 13:

Oxygen Sensor Circuit:

CIRCUIT DESCRIPTION:

The Oxygen Sensor (02) produces a varying voltage after the sensor is hot, above 360°C (600°F). This voltage varies from 0 to 900 mV. The signal will vary depending on the content of the exhaust gases. After the sensor is hot, if the voltage stays above 450 mV for more than 10 seconds, this indicates a rich condition. If voltage remains below 450 mV for 10 seconds, a lean condition is indicated. The 02 Sensor acts like an "open circuit" and produces no voltage when below 360°C (600°F). An open sensor circuit causes the engine to operate in an "open loop" operation.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. O2 sensor output voltage, at this step, should be fluctuating between 0-1 volt.

2. When the vacuum hose is removed from the MAP sensor, its output voltage will increase, and the ECM should interpret this as a high engine load. The ECM should increase the fuel injector pulse width, causing a rich A/F mixture. This should cause the O2 sensor to generate a high output voltage, usually more than 0.900 volt (900 mV).

DIAGNOSTIC AIDS:

Normal voltage varies between 0 mV and 900 mV. A loose or intermittent oxygen sensor ground circuit could cause a Code 13. The grounding point at the engine is located on the rear of the intake manifold, on the lower right edge.