Refer to Engine Controls Schematics .
Circuit Description
The heated oxygen sensor (HO2S 2), located in the exhaust stream past the catalytic converter, produces an output signal relative to the oxygen storage capacity of the catalytic converter. The powertrain control module (PCM) can then determine the ability of the catalytic converter to convert the exhaust emissions effectively. The HO2S 2 signal will be far less active than the signal produced by the front oxygen sensor 1 (O2S 1).
Conditions for Running the DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0172, P0201, P0202, P0203, P0204, P0300, P0301, P0302, P0303, P0304, P0336, P0440, P0446, P0452, P0453, P0506, P0507, P0601, P0602 or P1441 are not set. |
| • | The engine coolant temperature (ECT) is more than 70°C. |
| • | Engine run time is more than 10 seconds. |
| • | The throttle position (TP) angle is between 8 percent and 50 percent for 4 seconds. |
| • | Above conditions are met for 3.8 seconds. |
| • | Closed Loop operation. |
| • | System voltage more than 11.7 volts. |
| • | Fuel level more than 10 percent . |
| • | Fuel ethanol composition less than 88 percent. |
Conditions For Setting The DTC
HO2S 2 remains below 43 mV for 150 seconds.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate after 2 consecutive ignition cycles in which the diagnostic runs with the malfunction present. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | A scan tool can clear the DTCs. |
Diagnostic Aids
Important: Never solder the HO2S wires. For proper wire and connector repair refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Use the scan tool in order to observe the Long Term FT values at the different RPM and the air flow conditions. The scan tool also displays the fuel trim cells, so the Long Term FT values can be checked in each of the cells in order to determine when the DTC may have set. If the conditions for this DTC exist, the Long Term FT values measure around 158 or more.
Inspect for the following conditions:
| • | A sensor pigtail may be mispositioned and contacting the exhaust manifold. |
| • | An intermittent ground in wire between the connector and the sensor. |
| • | A poor PCM ground. |
| • | Lean injectors--Perform the Injector Balance Test. Refer to Fuel Injector Balance Test . |
| • | Fuel Contamination--Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can also set this DTC. |
| • | Fuel pressure--If the pressure is too low, the system will be lean. In order to confirm, monitor a fuel pressure gauge while driving the vehicle at various speeds and loads. Refer to Fuel System Diagnosis . |
| • | Exhaust leaks--If there is an exhaust leak, the engine may pull the outside air into the exhaust and past the sensor. Refer to Exhaust Leakage in Engine Exhaust. |
| • | Vacuum or crankcase ventilation system leaks can cause a lean condition or possibly a high idle. |
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Powertrain On-Board Diagnostic (OBD) System Check prompts you to complete some of the basic checks and to store the Freeze Frame and Failure Records data on the scan tool, if applicable. This creates an electronic copy of the data that was captured when the malfunction occurred. The scan tool stores this information for later reference.
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This step determines if DTC P0137 is the result of a hard malfunction or an intermittent condition.
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It is necessary to jump the HO2S 2 low circuit to ground in order to allow the PCM to display the supplied bias voltage. The PCM and the wiring are OK if the voltage is between 0.35 volts and 0.55 volts.
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Reprogram the replacement PCM and perform the Crankshaft Position System Variation Learn Procedure. Refer to the latest Techline™ information for PCM programming.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | |||||||
Is the HO2S 2 voltage less than the specified value? | 200 mV (0.20 V) | |||||||
3 |
Is the HO2S 2 voltage less than the specified value? | 40 mV (0.04 V) | ||||||
Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury. Does the scan tool indicate the HO2S 2 voltage within the specified value? | 350 mV-550 mV (0.35 V-0.55 V) | |||||||
5 |
Was a repair necessary? | -- | ||||||
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||||||
7 |
Is the action complete? | -- | -- | |||||
8 |
Does the scan tool indicate that this diagnostic has Run and Passed? | -- | ||||||
9 | Check to see if any additional DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to applicable DTC table | System OK |
