For 1990-2009 cars
Engine Controls Components
Oxygen Sensors
OBD II Symbol Description Notice
Engine Controls Connector End Views
Handling ESD Sensitive Parts Notice

### 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

• | DTC's P0106, P0107, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0506, P0507, P1406, P1441 not set.

• | Engine has been running for at least 30 seconds.

• | Engine Coolant Temperature (ECT) is greater than 70° C (158° F).

• | Throttle Position (TP) angle is between 8 % and 56 % for 20 seconds.

• | 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

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and 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 information is then stored on the scan tool for later reference.

2. During the engine warm-up, the O2S 1 should warm-up and its voltage output should vary between 150 mV and 850 mV. When the O2S 1 voltage varies, the engine will go into Closed Loop . This step determines if the O2S 1 is operating properly.

3. This will determine if the O2S 1 sensor is malfunctioning or the wiring or PCM is the cause of the DTC P0134.

4. Use only a high impedance digital volt ohmmeter for this test. This test checks the continuity of O2S 1 signal and the ground circuits, if the ground circuit is open, the PCM voltage on the signal circuit will be over 0.6 volt (600 mV).

5. The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be preformed. Refer to the latest Techline procedures for PCM reprogramming and Powertrain Control Module (PCM) for the Crankshaft Position System Variation Procedure .

#### DTC P0134-Oxygen Sensor (O2S) Circuit Insufficient Activity Detected (Sensor 1)

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Install a scan tool.
2. Run the engine above the specified operating temperature.
3. Operate the engine above the specified RPM for 2 minutes.

Does the scan tool indicate Closed Loop?

80°C (176°F)

1200 RPM

Go to Step 3

Go to Step 4

3 |

1. Turn the ignition switch ON, with the engine OFF.
2. Review the Freeze Frame data and note the parameters.
3. Operate the vehicle within the Freeze Frame conditions and Conditions For Setting The DTC as noted.

Does the scan tool indicate Closed Loop?

--

Go to Step 12

Go to Step 4

4 |

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

1. Turn the ignition switch ON, with the engine OFF.
2. Disconnect the O2S 1 electrical connector and jumper the O2S 1 sensor signal circuit (PCM side) to ground.

Is the O2S 1 voltage below the specified value?

50 mV (0.05V)

Go to Step 5

Go to Step 6

5 |

1. Check the O2S 1 electrical connector (PCM side) for malfunctioning terminals or poor connection and repair as necessary.
2. Refer to Electrical Diagnosis portion of the service manual.

Was a repair necessary?

--

Go to Step 12

Go to Step 9

6 |

1. Turn the ignition switch ON, with the engine OFF.
2. Remove the jumper wire.
3. Using a DVM, measure the voltage between the O2S 1 sensor signal circuit (PCM side) and the ground.

Does the O2S 1 voltage measure above the specified value?

600 mV (0.6V)

Go to Step 10

Go to Step 7

7 | Does the O2S 1 voltage measure below the specified value? | 300 mV (0.3V) | Go to Step 11 | Go to Step 8
8 | Replace the PCM. Is the action complete? | -- | Go to Step 12 | --
9 | Replace the O2S 1 sensor. Is the action complete? | -- | Go to Step 12 | --
10 | Check the O2S 1 sensor ground circuit for an open or poor connection and repair as necessary. Was a repair necessary? | -- | Go to Step 12 | Go to Step 8
11 | Check the O2S 1 sensor signal circuit for an open or poor connection and repair as necessary. Was a repair necessary? | -- | Go to Step 12 | Go to Step 8
12 |

1. If disconnected, reconnect the O2S 1 electrical connector.
2. Using the scan tool, clear the DTCs.
3. Start the engine and idle at normal operating temperature.
4. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has ran and passed?

--

Go to Step 13

Go to Step 2

13 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK