For 1990-2009 cars
Engine Controls Components
Cell 23: Oxygen Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views With EGR
Handling ESD Sensitive Parts Notice

### Circuit Description

The Powertrain Control Module (PCM) supplies a voltage of approximately 0.45 volt between the oxygen sensor (O2S 1) signal and the ground circuit. The oxygen sensor (O2S 1) varies the voltage within a range of approximately 1 volt if the exhaust is rich, to approximately 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.

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

### Conditions For Running The DTC (With EGR)

• | DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0171, P0200, P0300, P0301, P0302, P0303, P0304, P0341, P0404. P0506, P0507, P0601, P0602 not set.

• | Air flow is greater than 3 grams per second.

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

• | Throttle Position (TP) angle is between 4% and 56% for 20 seconds.

• | Engine run time is greater than 30 seconds.

### Conditions For Running The DTC (Without EGR)

• | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0200, P0300, P0301, P0302, P0303, P0304, P0335, P0440.P0442, P0446, P0506, P0507, P0601, P0602, or P1441 not set.

• | Air flow is greater than 3 grams per second.

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

• | Throttle Position (TP) angle is between 4% and 56% for 20 seconds.

• | Engine run time is greater than 30 seconds.

### Conditions For Setting The DTC

O2S 1 voltage is between 399 mV and 499 mV for 125 seconds.

### Action Taken When the DTC Sets (With EGR)

• | 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.

### Action Taken When the DTC Sets (Without EGR)

• | The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.

• | 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 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 numbers below refer to the step numbers on the Diagnostic Table.

1. 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 malfunction occurred. The scan tool stores this data for later reference.

2. 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.

3. 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.

4. 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).

5. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Techline information for PCM programming and the Crankshaft Position System Variation Learn for the crankshaft position system variation learn procedure.

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

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

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

Does the scan tool indicate a Closed Loop operation?

80°C (176°F)

1,200 RPM

Go to Step 3

Go to Step 4

3 |

1. Review the Freeze Frame data and record the parameters.
2. Operate the vehicle within the Freeze Frame conditions and Conditions For Running The DTC as specified.

Does the scan tool indicate a Closed Loop operation?

--

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 OFF the ignition switch.
2. Disconnect the O2S 1 sensor electrical connector.
3. Turn ON the ignition switch leaving the engine OFF.
4. Connect a jumper wire to the O2S 1 sensor signal circuit terminal (PCM side) to ground.

Is the O2S 1 voltage below the specified value?

50 mV (0.05 V)

Go to Step 5

Go to Step 6

5 |

1. Turn OFF the ignition switch.
2. Check for the following conditions in the O2S 1 electrical connector (PCM side):

• | Terminal connections

• | Poor electrical connections

3. Repair the malfunctioning terminals or the poor electrical connection as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 9

6 |

1. Remove the jumper wire.
2. Connect a DMM to ground.
3. Measure the voltage between the O2S 1 sensor signal circuit terminal (PCM side) and the ground.

Does the O2S 1 voltage measure above the specified value?

600 mV (0.6 V)

Go to Step 10

Go to Step 7

7 | Does the O2S 1 voltage measure below the specified value? | 300 mV (0.3 V) | Go to Step 11 | Go to Step 8
8 |

1. Turn OFF the ignition switch.
2. Replace the PCM. Refer to the Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 12

--

9 | Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury. Replace the O2S 1 sensor. Refer to the Oxygen Sensor Replacement . Is the action complete? | -- | Go to Step 12 | --
10 |

1. Turn OFF the ignition switch.
2. Check for the following conditions in the O2S 1 sensor ground circuit:

• | Open circuit

• | Poor electrical terminal connection

3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 8

11 |

1. Turn OFF the ignition switch.
2. Check for the following conditions in the O2S 1 sensor signal circuit:

• | Open circuit

• | Poor electrical terminal connection

3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 8

12 |

1. Reconnect the O2S 1 electrical connector if the connector is disconnected.
2. Turn ON the ignition switch leaving the engine OFF.
3. Clear the DTCs with the scan tool.
4. Start the engine.
5. Idle the engine at the normal operating temperature.
6. Operate the vehicle within the conditions for running 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 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