2010 Cadillac CTS Sedan AWD V6-3.6L Page 1061
Typical Scan Tool Data
Circuit Description
The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding
air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the
HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450
mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above
and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control
module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a
rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed
Loop earlier and the control module to calculate the air-to-fuel ratio sooner.
Conditions for Running the DTC
Condition 1
* DTC P0201, P0202, P0203, P0204, P0205, P0206 P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276,
P0277, P2146, P2149, P2152, P2155, P216A, or P216D is not set.
* The ignition voltage is greater than 10 volts.
* The engine speed is greater than 240 RPM.
* The air flow into the engine is greater than 220 grams.
* The HO2S 1 heater duty cycle is greater than 90 percent for greater than 5 seconds.
* The evaporative emissions system (EVAP) is not performing an intrusive test.
* The ECM is not commanding the air/fuel mixture lean.
* DTC P0131 and P0151 run continuously once the conditions above exist for greater than 5 seconds.
Condition 2
* DTC P0116, P0117, P0118, P0119, P0201, P0202, P0203, P0204, P0205, P0206 P0261, P0262, P0264, P0265, P0267, P0268, P0270,
P0271, P0273, P0274, P0276, P0277, P2146, P2149, P2152, P2155, P216A, or P216D is not set.
* The ignition voltage is greater than 10 volts.
* The engine speed is greater than 240 RPM.
* The conditions for a cold start are present.
* The HO2S 1 heater duty cycle is greater than 90 percent.
* DTC P0131 and P0151 run continuously once the conditions above exist for greater than 5 seconds.
Conditions for Setting the DTC
Condition 1
The ECM detects that an HO2S 1 signal voltage is less than 60 mV while the corresponding HO2S 2 voltage is greater than 500 mV.
Condition 2
The ECM detects that an HO2S 1 signal voltage is less than 60 mV after a cold start.
Action Taken when the DTC Sets
DTCs P0131 and P0151 are Type B DTCs.
