P013

DTC PO13:

Oxygen Sensor Circuit:

DESCRIPTION
The Powertrain Control Module (PCM) provides a 0.45 volt reference to the oxygen sensor on CKT 1670. When the oxygen sensor reaches operating temperature it will generate a counter voltage that will vary based on the amount of oxygen in the exhaust. The rear oxygen sensor is located in the manifold before the catalytic convertor. A lean exhaust will generate a low voltage and cause the 0.45 reference to move lower. A rich exhaust will generate a high voltage and cause the 0.45 reference voltage to move higher. If the oxygen sensor can't respond under the test conditions and generate a voltage greater or less than the 0.45 reference voltage, it will set a Code P013. Possible causes of Code PO13 are:

1. Open in CKT 1670 or 1671.
2. Short to voltage on CKT 1670 or 1671.
3. Oxygen sensor that cannot respond.

TEST CONDITIONS
1. Codes PO14, PO15, PO21, PO22, PO26, and PO27 not set.
2. Coolant temperature 81.5°C (179°F) or greater.
3. Throttle angle between 5.0 and 29.8 degrees.
4. Throttle position switch open.
5. Engine speed 800 rpm or greater.

FAILURE CONDITIONS
Oxygen sensor voltage stays between 0.307 volt and 0.609 volt for more than 64 seconds (oxygen sensor voltage not toggling), Code P013 is set.

ACTION TAKEN
1. PCM turns "ON" the "Service Engine Soon" Malfunction Indicator Lamp (MIL).
2. PCM enables evaporative emission control solenoid if Code P017 is also set.
3. "Closed Loop" operation disabled.

NOTES ON FAULT TREE
1. Voltage on PCM data parameter PD33 should fluctuate above 0.6 volt and below 0.3 volt. If voltage remains above 0.6 volt, check CKT 1670 for a short to voltage. If voltage remains below 0.3 volt check CKT 1670 for a short to ground.

2. Measuring voltage with a voltmeter will isolate a sensor/wiring problem from a PCM problem. If voltage fluctuates above 0.6 volt and below 0.3 volts, the fault is with the PCM. If voltage remains below 0.3 volt, check CKT 1670 for a short to ground or CKT 1671 for a short to voltage. If voltage remains above 0.6 volt, check CKT 1670 for a short to voltage. If voltage remains between 0.3 volt and 0.6 volt, check CKT 1670 and CKT 1671 for an open.