Circuit Description
The Powertrain Control Module (PCM) supplies a voltage of about 0.45 volt between the O2S signal and the ground circuit. The Oxygen Sensor (O2S 1) varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if the exhaust is lean.
The sensor is like an open circuit and produces no voltage when below 315°C (600°F). An open sensor circuit or a cold sensor causes an Open Loop operation.
If there is damage to the oxygen sensor pigtail wiring, the connector or the terminal, replace the entire oxygen sensor assembly. Do not attempt to repair the wiring, the connector or the terminals. The sensor must have a clean air reference provided in order to function properly. This clean air reference is obtained by way of the oxygen sensor wire(s). Any attempt to repair the wires, the connectors or the terminals could result in the obstruction of the air reference and degrade the oxygen sensor performance. Refer to Heated Oxygen Sensor (O2S) Repair.
Conditions for Setting the DTC
| • | DTCs P0106, P0107, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0506, P0507, P1336, P1404, P1441 not set. |
| • | The engine has been running for at least 30 seconds. |
| • | The Engine Coolant Temperature (ECT) is greater than 70°C (158°F). |
| • | The Throttle Position (TP) angle is between 8 percent and 56 percent for 20 seconds. |
| • | The O2S 1 voltage is between 399 mV and 499 mV for 125 to 150 seconds. |
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will illuminate. |
| • | 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 stores. |
| • | The coolant fan turns ON. |
| • | The vehicle will operate in an Open Loop operation. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after three 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. |
| • | The MIL/DTCs can be cleared by using the scan tool. |
Diagnostic Aids
The normal scan tool voltage varies between 150 mV to 850 mV (0.15 volt to 0.85 volt) while in a Closed Loop operation.
An intermittent could be the result of the following conditions:
| • | A poor electrical connection |
| • | Rubbed-through wire insulation |
| • | A broken wire inside the insulation |
Check for a poor electrical connection or a damaged harness. Inspect the harness electrical connectors for the following conditions:
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed electrical connectors |
| • | Damaged terminals |
| • | A poor terminal-to-wire connection |
| • | A damaged harness |
Replace the entire oxygen sensor (O2S 1) assembly. Do not attempt to repair the oxygen sensor if the following conditions exist:
| • | Damaged wiring |
| • | Damaged electrical connectors |
| • | Damaged terminals |
Test Description
The number(s) below refer(s) to the step number(s) on the Diagnostic Table.
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The Powertrain 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 taken when the fault occurred. The scan tool stores this data for later reference.
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During the engine warm-up, the O2S 1 should warm-up and the voltage output should vary between 150 mV and 850 mV. When the O2S 1 voltage varies, the engine will go into a Closed Loop operation. This step determines if the O2S 1 sensor is operating properly.
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This step will determine if the O2S 1 sensor is malfunctioning, or if the wiring or the PCM is the cause of the DTC P0134.
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Use only a high impedance digital volt ohmmeter for this test. This test checks the continuity of O2S 1 sensor signal circuit and the O2S 1 sensor low circuit; if the O2S 1 sensor low circuit is open, and if the PCM voltage on the O2S 1 sensor signal circuit will be over 0.6 volt (600 mV).
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Reprogram the replacement PCM and perform the crankshaft position system variation learning procedure. Refer to the latest Techline information for PCM programming and the Powertrain Control Module (PCM) for the crankshaft position system variation learning procedure.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | |||
Does the scan tool indicate a Closed Loop operation? | 80°C (176°F) 1200 RPM | |||
3 |
Does the scan tool indicate a Closed Loop operation? | -- | ||
Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury. Is the O2S 1 voltage below the specified value? | 50 mV (0.05 V) | |||
5 |
Was a repair necessary? | -- | ||
Does the O2S 1 voltage measure above the specified value? | 600 mV (0.6 V) | |||
7 | Does the O2S 1 voltage measure below the specified value? | 300 mV (0.3 V) | ||
Replace the PCM. Is the action complete? | -- | -- | ||
9 | Replace the O2S 1 sensor. Is the action complete? | -- | -- | |
10 | Check the O2S 1 sensor ground circuit for an open connection or a poor connection. Repair the circuit as necessary. Was a repair necessary? | -- | ||
11 | Check the O2S 1 sensor signal circuit for an open or poor connection. Repair the circuit as necessary. Was a repair necessary? | -- | ||
12 |
Does the scan tool indicate that this diagnostic has ran and passed? | -- | ||
13 | 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 |
