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DTC P0136 (LLU)

DTC P0136 (LLU)

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category.


DTC Descriptor

DTC P0136 00

HO2S Circuit Sensor 2

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Signal Circuit

P0136 00, P0137 00

P0136 00, P0137 00

P0136 00, P0138 00, P0606 00

P0137 00

Low Reference

-

P0136 00, P0137 00

-

P0137 00



Typical Scan Tool Data

HO2S 2

Circuit Short to Ground Open Short to Voltage
Operating Conditions: The engine operating in closed loop with high exhaust system temperatures

Parameter Normal Range: Fluctuates above and below 350-500 mV

Heated Oxygen Sensor 2 Signal

15 mV

55 mV*

1275 mV

Low Reference

-

55 mV*

-

*Voltage varies slightly with sensor/exhaust system temperature



Circuit/System Description

The heated oxygen sensor (HO2S) 2 circuit diagnostics monitors the voltage on the signal circuit of the post catalyst oxygen sensor. In order to control emissions of hydrocarbons, carbon monoxide (CO), and oxides of nitrogen (NOX), a 3-way catalytic converter is used. The catalyst within the converter promotes a chemical reaction which oxidizes the hydrocarbons and CO present in the exhaust gas, converting the hydrocarbons and the CO into harmless water vapor and carbon dioxide. The catalyst also reduces NOX by converting the NOX to nitrogen. The engine control module (ECM) has the ability to monitor this process using the heated oxygen sensors 1 and heated oxygen sensor 2. The heated oxygen sensor 1 produces an output signal which indicates the amount of oxygen present in the exhaust gas entering the 3-way catalytic converter. The heated oxygen sensor 2 produces an output signal which indicates the oxygen storage capacity of the catalyst. This in turn indicates the catalysts ability to convert exhaust gases efficiently. If the catalyst is operating efficiently, the heated oxygen sensor 1 signal will be far more active than that produced by the heated oxygen sensor 2.

The heated oxygen sensor 2 utilizes the following circuits:


• A signal circuit

• A low reference

• An ignition voltage circuit

• A heater control circuit


Conditions for Running the DTC


• DTC P0031 00, P0032 00, P0037 00, P0038 00, P0112 00, P0113 00, P0117 00, P0118 00, P0121 00, P0122 00, P0123 00, P0171 00, P0172 00, P0300 00 - P0304 00, P0335 00, or P0341 00 are not set.

• The battery voltage is greater than 10 V.

• The engine coolant temperature (ECT) is greater than or equal to 75°C (167°F).

• The engine speed is greater that 25 RPM

• The engine is operating in closed loop fuel control.

• DTC P0136 00 runs once per drive cycle when the above conditions are met for 10 min.


Conditions for Setting the DTC


• The average heated oxygen sensor 2 voltage is greater than or equal to 500 mV.

or

• The average heated oxygen sensor 2 voltage is less than or equal to 400 mV.


Action Taken When the DTC Sets

DTCs P0136 00 is a Type B DTC.

Conditions for Clearing the DTC

DTCs P0136 00 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference


• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs

• Heated Oxygen Sensor Wiring Repairs


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification


1. Clear the DTCs with a scan tool.

2. 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

Note

You must perform the circuit/system verification before proceeding with circuit/system testing.



1. Ignition OFF, disconnect the harness connector at the B52B Heated Oxygen Sensor 2.

2. Ignition OFF, measure for less than 5 Ω between the B52B Heated Oxygen Sensor 2 low signal circuit terminal 3 and ground.

3. If greater than the specified range, test the low signal circuit for the B52B heated oxygen sensor 2 for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.

4. Ignition ON, verify the HO2S 2 scan tool HO2S Sensor 2 parameter is approximately 450 mV.

5. If greater than the specified value, test the high signal circuit terminal 4 for the B52B heated oxygen sensor 2 for a short to voltage. If the circuit tests normal, replace the K20 engine control module.

6. If lower than the specified value, test the high signal circuit terminal 4 for the B52B heated oxygen sensor 2 for a short to ground. If the circuit tests normal, replace the K20 engine control module.

7. Ignition ON, install a 3 A fused jumper wire at the B52B Heated Oxygen Sensor 2 high signal circuit terminal 4. Toggle the jumper wire between the B52B Heated Oxygen Sensor 2 low signal circuit terminal 3 and battery voltage. Verify the HO2S 2 scan tool HO2S Sensor 2 parameter toggles between 0 mV and approximately 1000 mV.

8. If the HO2S 2 scan tool HO2S Sensor 2 parameter does not toggle correctly, test the B52B Heated Oxygen Sensor 2 high signal circuit terminal 4 for an open/high resistance. If the circuits test normal, replace the K20 Engine Control Module.

9. If all circuits test normal, replace the appropriate B52B Heated Oxygen Sensor 2.


Repair Instructions

Refer to Heated Oxygen Sensor Resistance Learn Reset Caution .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Heated Oxygen Sensor Replacement - Sensor 2

• Control Module References for ECM replacement, setup, and programming