DTC 13

Code 13 Open Oxygen Sensor Circuit:

Fig. 024a Oxygen Sensor Circuit:

CODE 13

OPEN OXYGEN SENSOR CIRCUIT

2.0L (VIN 1)

FUEL INJECTION (TBI)

Circuit Description The ECM supplies a voltage of about .45 volts between terminals "E14" and "E15". (If measured with a 10 megogm digital voltmeter, this may read as low as .32 volts).
The O(2) sensor varies the voltage within 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 degrees C (600 degrees F). An open sensor circuit, or cold sensor, causes "Open Loop" operation.

TEST DESCRIPTION Numbers below refer to circled numbers on Diagnostic Charts.

1. Code 13 WILL SET:
Engine at normal operating temperature.
At least 2 minutes engine run time after start.
O(2) signal voltage steady between .35 and .55 volts.
Throttle angle above 7%.
All conditions must be met for about 20 seconds.
If the conditions for a Code 13 exist, the system will not go "Closed Loop"
2. This test determines if the O(2) sensor is the problem, or, if the ECM and wiring are at fault.
3. In doing this test, use only a high impedance digital volt ohm meter. This test checks the continuity of CKTs 412 and 413. If CKT 413 is open, the ECM voltage on CKT 412 will be over .6 volts (600 mv).

Diagnostic Aids: Normal "Scan" voltage varies between 100 mv to 999 mv (.1 and 1.0 volt), while in "Closed Loop". Code 13 sets in one minute, if voltage remains between .35 and .55 volts, but the system will go "Open Loop" in about 15 seconds.
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