Powertrain Controls - ECM/PCM

DTC 63 Chart:

Right (Bank 1) Oxygen Sensor Circuit:

Circuit Description:
The PCM supplies a voltage of about .55 volt between terminals "B22" and "B23." (If measured with a 10 megohm digital voltmeter, this may read as low as .35 volt.) The Oxygen Sensor (02S) varies the voltage within a range of about 1 volt. If the right (Bank 1) exhaust is rich, the 02S will display close to 1000 millivolts and when the exhaust is lean the 02S will display close to 100 millivolts.

The sensor is like an open circuit and produces no voltage when it is below 316°C (600°F). An open 02S circuit or cold 02S causes "Open Loop" operation.

DTC 63 Will Set When:
Vehicle is operating in "Closed Loop," engine coolant temperature greater than 85°C (185°F), CKT 1666 voltage steady between 350 millivolts and 550 millivolts, throttle angle greater than 3% with all conditions met and held for 30 seconds.

Action Taken (PCM will default to):
Vehicle will operate in "Open Loop" and MIL will become illuminated.

DTC 63 Will Clear When:
A current DTC 63 will clear when the 02S voltage falls out of the 350 to 550 millivolt range. A history DTC 63 will clear after 50 consecutive ignition key cycles without a current DTC 63 being stored.

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

1. If the conditions for a DTC 63 exist, the system will not go "Closed Loop."

2. This will determine if the sensor is a fault or the wiring or PCM is the cause of the DTC 63.

3. In doing this test use only a high impedance digital volt ohmmeter. This test checks the continuity of CKT 1666 and CKT 351 because if CKT 351 is open, the PCM voltage on CKT 1666 will be greater than .6 volt (600 mV).

Diagnostic Aids:
Normal Tech 1 scan voltage varies between 100 mV 999 mV (.1 and 1.0 volt) while in "Closed Loop." DTC 63 sets if voltage remains between 350 millivolts and 550 millivolts, but the system will go "Open Loop" in about 15 seconds. Refer to "Intermittents" in "Diagnosis By Symptom." - Intermittent Malfunctions