DTC P0150 HO2S Circuit Closed Loop (CL) Performance Bank 2 Sensor 1. Cadillac Eldorado 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 DTC P0150 HO2S Circuit Closed Loop (CL) Performance Bank 2 Sensor 1

Engine Controls Component Views
Heated Oxygen Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The heated oxygen sensor (HO2S) is a sensor used to detect oxygen-content in the exhaust. The powertrain control module (PCM) supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, the PCM adjusts the injector pulse width. If the signal frequency of HO2S bank 2 sensor 1 indicates an active sensor (closed loop), but the amplitude (voltage) of the signal remains within a calibrated range, DTC P0150 will set.

Conditions for Running the DTC

•	No TP sensor, MAF sensor, MAP sensor, ECT sensor, HO2S, or fuel injector DTCs are set.

•	ECT is more than 75°C (167°F).

•	Engine run time is more than 120 seconds (2 minutes).

•	Predicted O2 heater temperature is more than 600°C (1112°F)

•	System voltage is between 9-18 volts.

•	MAF is between 3-30 g/s.

•	Engine speed is between 500-5000 RPM.

•	Traction control is inactive

•	Catalyst test is inactive

•	Deceleration Fuel Cut Off (DFCO) is inactive.

•	Power Enrichment (PE) is inactive.

•	Conditions above met for 5 seconds.

•	Closed loop fuel control is enabled.

Conditions for Setting the DTC

•	The vehicle is in closed loop fuel control (based on HO2S bank 1 sensor 1 and bank 2 sensor 1 voltages switching from below 350 mV to above 500 mV).

•	During a 120 second monitoring period, the HO2S bank 2 sensor 1 voltage remains within 350-500 mV for approximately 16 seconds.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.

•	The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.

•	The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions in Symptoms.

Step

Action

Values

Yes

Did you perform the Powertrain On Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

With the engine at operating temperature, raise and hold the engine speed above 1200 RPM for two minutes.
Monitor the HO2S bank 2 sensor 1 voltage display on the scan tool.

Does the scan tool indicate HO2S bank 2 sensor 1 voltage varying outside the specified values?

350-500 mV

Go to Step 3

Go to Step 4

Turn ON the ignition, with the engine OFF.
Review and record scan tool Fail Records data.
Operate the vehicle within the Fail Records conditions.
With the scan tool, monitor the Specific DTC Information for DTC P0150 until the test runs.

Does the scan tool indicate DTC failed last test?

Go to Step 4

Go to Diagnostic Aids

Disconnect the HO2S bank 2 sensor 1 harness connector.
Turn ON the ignition, with the engine OFF.
Jumper the HO2S bank 2 sensor 1 signal and low circuits in the harness connector (PCM side).
Observe the HO2S bank 2 sensor 1 voltage display on the scan tool.

Does the scan tool indicate an HO2S bank 2 sensor 1 voltage below the specified value?

150 mV

Go to Step 6

Go to Step 5

Turn OFF the ignition.
Disconnect the PCM connector C1. Refer to Powertrain Control Module Replacement/Programming .
Test for the following conditions:

•	Open signal circuit

•	Open low circuit

•	Poor connections at the PCM, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

Inspect for poor connections at the HO2S bank 2 sensor 1 harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

Important: If the sensor appears contaminated, correct the source of the oxygen sensor contamination before replacing the sensor in order to prevent future contamination. Typical contamination sources include the following:

•	Fuel contamination, refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Use of improper RTV sealant

•	Engine oil or engine coolant consumption, refer to Oil Consumption Diagnosis in Engine Mechanical.

Replace HO2S bank 2 sensor 1. Refer to Heated Oxygen Sensor Replacement - Bank 2 .

Is the action complete?

Go to Step 9

Important:: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

Go to Step 9

Turn ON the ignition, with the engine OFF.
Review and record scan tool Fail Records data.
Clear DTCs.
Operate the vehicle within Fail Records conditions as noted.
With a scan tool, monitor Specific DTC info for DTC P0150 until the test runs.

Does the scan tool indicate DTC P0150 passed?

System OK

Go to Step 2