P0153

Diagnostic Chart:

CIRCUIT DESCRIPTION

The Heated Oxygen Sensor (HO2S) produces a voltage that varies between -100 mV and 900 mV under normal operating conditions. On the Catera, the full operating range of the HO2S circuit is approximately from -406 mV to 1124 mV. The Engine Control Module (ECM) monitors this voltage and determines if the exhaust is lean or rich. The oxygen sensor voltage is high when the exhaust is rich, and low when the exhaust is lean. The ECM constantly monitors the HO2S signal during the closed loop operation and compensates for a rich or lean condition by decreasing or increasing the injector pulse width as necessary. If the oxygen sensor is slow to respond to any changes in the exhaust oxygen content, this DTC will set.

CONDITIONS FOR RUNNING THE DTC

^ P0120, P0135, P0141, P0155, P0161, P0340, P0440, P0441, P0442, P0443, P0455, P0300, P0301, P0302, P0303, P0304, P0305, P0306, and P0560 not set.

^ A closed loop operation

^ The engine speed is between 1,000 RPM and 2,000 RPM.

^ The engine load signal is between 1.3 ms and 3.0 ms.

^ The calculated TWC temperature is greater than 352°C (666°F).

^ More than 6 seconds have passed since the purge enabled.

CONDITIONS FOR SETTING THE DTC

The HO2S averaged response rate is greater than 3.3 seconds.

ACTION TAKEN WHEN THE DTC SETS

The ECM illuminates the Malfunction Indicator Lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The ECM turns off the MIL after three consecutive drive trips that the diagnostic runs and does not fail.

^ A History DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other emission related diagnostic.

^ The ECM battery voltage is interrupted.

^ The scan tool clears the MIL/DTC.

DIAGNOSTIC AIDS

Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

^ The sensor pigtail or the harness may be mis-positioned and contacting the exhaust system.

^ Heated oxygen sensor wiring. Inspect the harness connectors for the following conditions:

- Backed out terminals

- Improper mating

- Broken locks

- Improperly formed or damaged terminals

- Poor terminal to wire connection

- Corrosion and water intrusion

Refer to Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact procedure. An oxygen supply inside of the HO2S is necessary for a proper operation. This supply of oxygen is provided through the HO2S wires. All of the HO2S wires and connections should be inspected for any breaks or any contamination. If any of the wiring repairs need to be made, refer to Overall Vehicle Information / Diagrams / Diagnostic Aids for electrical inspection and repair procedures.

^ Poor ECM to engine grounds

^ Fuel pressure. If the fuel pressure is too low, this DTC may be set. Refer to Fuel System Diagnosis. System Diagnosis - Fuel System

^ Lean injector(s)

^ Vacuum leaks. Check for any disconnected or damaged vacuum hoses and for vacuum leaks at the intake manifold, the throttle body, and the crankcase ventilation system.

^ Exhaust leaks. An exhaust leak may cause the outside air to be pulled into the exhaust gas stream past the HO2S, causing this DTC to set. Check for any exhaust leaks near the HO2S.

^ Fuel contamination. Water, even in small amounts, can be delivered to the fuel injectors. The water can cause a lean exhaust to be indicated. Excessive alcohol in the fuel can also cause this condition. Refer to Fuel System Diagnosis for the procedure in order to check for any fuel contamination. System Diagnosis - Fuel System

^ If the above are OK, the HO2S may be at fault.

TEST DESCRIPTION

The number(s) below refer to the step numbers on the diagnostic table.

2. The engine must be at the normal operating temperature before performing this test.