Circuit Description
The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensors rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground, to maintain a desired temperature.
The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.
The HO2S utilizes the following circuits:
A signal circuit
A low reference circuit
An ignition voltage circuit
A heater control circuit
Conditions for Running the DTC
P0030, P0031, P0032, P0050, P0051, P0052
The ignition voltage is between 10-18 volts.
The engine speed is greater than 240 RPM.
The HO2S heater is commanded ON.
The DTCs run continuously once the above conditions are met for 5 seconds.
P0036, P0037, P0038, P0056, P0057, P0058
The ignition voltage is between 10-18 volts.
The engine speed is greater than 80 RPM.
The HO2S heater is commanded ON and OFF at least once during the ignition cycle.
The HO2S 2 is at operating temperature.
The DTCs run continuously once the above conditions are met.
Conditions for Setting the DTC
P0030, P0036, P0050, and P0056
The ECM detects an open in the heater circuits of the HO2S when the heater is commanded OFF. The condition exists for greater than 4 seconds or a cumulative of 30 seconds.
P0031, P0037, P0051, and P0057
The ECM detects a short to ground in the heater circuits of the HO2S when the heater is commanded OFF. The condition exists for greater than 4 seconds or a cumulative of 30 seconds.
P0032, P0038, P0052, and P0058
The ECM detects a short to voltage in the heater circuits of the HO2S when the heater is commanded ON. The condition exists for greater than 4 seconds or a cumulative of 30 seconds.
Action Taken When the DTC Sets
DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, and P0058 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, and P0058 are Type B DTCs.
Diagnostic Aids
If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool circuit test status parameters for the component. The circuit test status parameters change from OK or Not Run to Fault if there is a condition with the circuit or a connection.
An open fuse in the HO2S heater circuit may be caused by the heater element in one of the sensors. The condition may not be present until the sensor operates for a period of time. If no fault is present in the heater circuit, monitor the amperage of each heater using the DMM to determine if one of the heater elements is the cause of the open fuse. Inspect the sensor pigtail or the harness for contacting the exhaust system.
Reference Information
Schematic Reference
Engine Controls Schematics (See: Diagrams Electrical Powertrain Management System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams Connector Views Connector End Views By Name)
Electrical Information Reference
Circuit Testing (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Circuit Testing Circuit Testing)
Connector Repairs (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Connector Repairs Connector Repairs)
Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Circuit Testing Testing For Intermittent Conditions and Poor Connections)
Wiring Repairs (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Wiring Repairs Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection Programming and Relearning)for scan tool information
Circuit/System Verification
Engine idling at operating temperature for at least 30 seconds. Observe the DTC information, DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, and P0058 should not set.
Observe the appropriate scan tool HO2S Heater Circuit Test Status parameter. The parameter should display OK or Not Run.
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Ignition OFF, disconnect the harness connector at the appropriate heated oxygen sensor (HO2S).
Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal D and ground.
Note: The ignition circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition circuit.
 If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition circuit and replace as necessary.
Connect a test lamp between the heater control circuit terminal E and B+. The test lamp should not illuminate.
 If the test lamp is always ON, test the control circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
Note: The control circuit for the HO2S heater is pulled-up to voltage within the ECM, 2.0-3.0 volts on the control circuit is normal.
Idle the engine, and verify the test lamp illuminates or flashes.
 If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
Ignition ON, test for 2.0-3.0 V between the control circuit terminal E and ground.
 If not within the specified range, test the control circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
If all circuits/connections test normal, test or replace the HO2S sensor.
Component Testing
Ignition OFF, disconnect the harness connector at the heated oxygen sensor (HO2S).
Test for 5-25 ohm between terminal D and E of the HO2S.
 If not within the specified range, replace the HO2S.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (See: Powertrain Management Computers and Control Systems Oxygen Sensor Service and Repair Heated Oxygen Sensor Replacement - Bank 1 Sensor 1)
Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (See: Powertrain Management Computers and Control Systems Oxygen Sensor Service and Repair Heated Oxygen Sensor Replacement - Bank 1 Sensor 2)
Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (See: Powertrain Management Computers and Control Systems Oxygen Sensor Service and Repair Heated Oxygen Sensor Replacement - Bank 2 Sensor 1)
Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (See: Powertrain Management Computers and Control Systems Oxygen Sensor Service and Repair Heated Oxygen Sensor Replacement - Bank 2 Sensor 2)
Control Module References (See: Testing and Inspection Programming and Relearning)for engine control module replacement, setup, and programming
DTC P2097 or P2099
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection Initial Inspection and Diagnostic Overview Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
Review Strategy Based Diagnosis (See: Testing and Inspection Initial Inspection and Diagnostic Overview Strategy Based Diagnosis) for an overview of the diagnostic approach.
Diagnostic Procedure Instructions (See: Testing and Inspection Initial Inspection and Diagnostic Overview Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P2097
Post Catalyst Fuel Trim System High Limit Bank 1
DTC P2099
Post Catalyst Fuel Trim System High Limit Bank 2
Circuit Description
Fuel trim bias is used to keep the post catalyst air/fuel ratio within a predetermined range. This allows optimal catalyst efficiency under light load conditions at a steady cruise. The engine control module (ECM) constantly monitors how lean or rich the fuel trim bias is commanded, to determine if the fuel trim bias is greater than a calibrated amount.
Conditions for Running the DTC
Before the ECM can report DTC P2097 or P2099 failed, DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P013A, P013C, P013E, P0130, P0131, P0132, P0133, P0135, P0137, P0138, P014A, P0140, P0141, P0150, P0151, P0152, P0153, P0155, P0157, P0158, P0160, P0161, P2232, P2235, P2270, P2271, P2272, and P2273 must run and pass.
DTC P0100, P0101, P0102, P0103, P0420, P0430, P0442, P0443, P0455, P0458, P0459, P2177, P2178, P2179, P2180, P2187, P2188, P2189 or P2190 is not set.
The engine speed is 1,280-3,480 RPM.
The engine load is 17-65 percent and steady.
The closed loop fuel control is active for greater than 1 second.
The calculated exhaust gas temperature is greater than 250°C (482°F).
DTC P2097 and P2099 run continuously when the conditions above have been met for greater than 130 seconds.
Conditions for Setting the DTC
The rich correction limit for a condition causing a lean air/fuel ratio has been exceeded for greater than 4 seconds or for a cumulative of 30 seconds.
Action Taken when the DTC Sets
DTCs P2097 and P2099 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2097 and P2099 are Type B DTCs.
Diagnostic Aids
An HO2S will not cause this DTC to set without the occurrence of circuit related HO2S DTCs. Do not replace an HO2S to address this DTC.
An exhaust system leak that may not be audible can set this DTC.
Reference Information
Schematic Reference
Engine Controls Schematics (See: Diagrams Electrical Powertrain Management System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams Connector Views Connector End Views By Name)
Electrical Information Reference
Circuit Testing (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Circuit Testing Circuit Testing)
Connector Repairs (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Connector Repairs Connector Repairs)
Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Circuit Testing Testing For Intermittent Conditions and Poor Connections)
Wiring Repairs (See: Testing and Inspection Component Tests and General Diagnostics General Electrical Diagnostic Procedures Wiring Repairs Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection Programming and Relearning)for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool DTC information. Verify there is no other HO2S or fuel trim DTC set.
 If any other HO2S or fuel trim DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions Diagnostic Trouble Code (DTC) List - Vehicle).
Verify that none of the following conditions exist:
Exhaust system leaks-Refer to Exhaust Leakage (See: Engine, Cooling and Exhaust Exhaust System Testing and Inspection Exhaust Leakage)
Engine vacuum leaks
Low fuel system pressure-Refer to Fuel System Diagnosis (See: Powertrain Management Computers and Control Systems Testing and Inspection Component Tests and General Diagnostics Fuel System Diagnosis).
Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (See: Powertrain Management Computers and Control Systems Testing and Inspection Component Tests and General Diagnostics Alcohol/Contaminants-in-Fuel Diagnosis).
Lean fuel injectors-Refer to Fuel Injector Solenoid Coil Test (See: Powertrain Management Computers and Control Systems Testing and Inspection Component Tests and General Diagnostics Fuel Injector Solenoid Coil Test).
 If you find any of the above conditions, repair as necessary.
Warning: Refer to Road Test Warning (See: Service Precautions Technician Safety Information Road Test Warning).
Note: A road load condition is necessary to obtain closed loop.
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
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Sunday, January 13th, 2013 AT 9:13 PM
