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

### Circuit Description

The PCM continuously monitors the Oxygen Sensor (O2S 1) activity for 100 seconds. During the monitor period, the PCM counts the number of times that the O2S 1 switches from rich to lean and from lean to rich and adds the amount of time that the O2S 1 took in order to complete all of the switches. With this information, you can determine an average time for all of the switches. If the average time to switch is too slow, a DTC P0133 will set.

Replace the entire oxygen sensor assembly if there is damage to the oxygen sensor pigtail wiring, the connector or the terminal. Do not attempt to repair the wiring, the connector or the terminals. The sensor must have a clean air reference provided in order for the sensor 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.

• | The average O2S 1 response times are greater than 249 mS for rich to lean sweeps or 249 mS for lean to rich sweeps.

| Or

• | Ratio of response times is greater than 3.25 or less than 0.4 (auto trans.).

• | Ratio of response times is greater than 3.4 or less than 0.4 (manual trans.).

• | Engine speed is between 1600 RPM and 2600 RPM.

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

• | Evaporative emissions control system is commanded open for greater than 36 % (auto trans.).

• | Evaporative emissions control system is commanded open for greater than 50 % (manual trans.).

• | Purge learned memory is greater than approximately 128. (auto trans.).

• | Purge learned memory is greater than approximately 191 (manual trans.).

### Action Taken When the DTC Sets

• | The malfunction indicator lamp (MIL) will illuminate after two 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 stores.

• | The coolant fan turns ON.

### 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

DTC P0133 or slow response is most likely caused by one of the following conditions:

• | Fuel pressure - The system will go rich if fuel pressure is to high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0133 may set. See Fuel System Diagnosis .

• | Leaking injector - A leaking or faulty injector can cause the system to go rich.

• | MAP sensor - An output that causes the PCM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected.

• | Pressure regulator - Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator.

• | TP sensor - An intermittent TP sensor output can cause the system to go rich due to a false indication of the engine accelerating.

• | O2S 1 contamination - Inspect O2S 1 for silicone contamination from fuel or use of improper RTV sealant. The sensor may have a white powdery coating and result in a high but false voltage signal (rich exhaust indication). The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem.

### 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 in the scan tool for later reference.

2. Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.

3. If no faults have been found at this point and no additional DTC's were set, refer to Diagnostic Aids for additional checks and information.

#### DTC P0133-Oxygen Sensor (O2S) Circuit Slow Response (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 | Were any component DTC's set? | -- | Go to Component DTC tables | Go to Step 3
3 |

1. Install a scan tool.
2. Engine running at operating temperature.
3. Operate the vehicle within the parameters specified under Conditions For Setting The DTC .
4. Monitor the Lean/Rich Avg. (mS), Rich/Lean Avg. (mS), and Rich/Lean to Lean/Rich Ratio Bank 1 Sensor. 1 (greater than, less than).

Do the parameters show averages less than the specified values or ratios less than or greater than the specified values?

249 ms

249 ms

0.4

3.4

Go to Step 4

Go to Step 18

4 | Visually/physical inspect the following items:

• | O2S 1 is securely installed.

• | Check for corrosion on the terminals.

• | Check for terminal tension (At O2S 1 and at the PCM).

• | Check the O2S 1 ground circuit for a good connection.

• | Check for damaged wiring.

Was a problem found in any of the above areas?

--

Go to Step 9

Go to Step 5

5 | Check the exhaust manifold for an exhaust leak near the engine. Repair as necessary. Was a exhaust leak found? | -- | Go to Step 3 | Go to Step 6
6 |

1. Ignition OFF.
2. Disconnect the O2S 1 at the sensor.
3. Using the scan tool, monitor the O2S 1 voltage.

Does the scan tool voltage indicate voltage within specified values?

407-509 mV

Go to Step 7

Go to Step 10

7 |

1. Jumper the O2S 1 high circuit (PCM side) signal circuit to ground.
2. Using the scan tool, monitor the O2S 1 voltage.

Does the scan tool voltage indicate the voltage below the specified value?

200 mV

Go to Step 8

Go to Step 11

8 | Notice: Determine and correct the cause of the contamination in order to prevent damage to the replacement sensors. Replace the Oxygen Sensor (O2S 1). Is the action complete? | -- | Go to Step 17 | --
9 | Repair the condition as necessary. Is the action complete? | -- | Go to Step 17 | --
10 | Repair the O2S 1 sensor signal circuit for a short to ground. Is the action complete? | -- | Go to Step 17 | --
11 |

1. Remove the jumper wire.
2. Using a DVM measure the voltage between the O2S 1 high signal circuit and ground.

Does the O2S 1 voltage measure above the specified value?

407 mV

Go to Step 12

Go to Step 13

12 |

1. Ignition OFF.
2. Disconnect the PCM connectors and check the O2S 1 low circuit for continuity
3. If the O2S 1 low circuit measures over the stated value, repair the open or poor connection as necessary.

Was an O2S 1 low circuit problem found and corrected?

5 ohms

Go to Step 17

Go to Step 14

13 |

1. Ignition OFF.
2. Disconnect the PCM connectors and check the O2S 1 sensor signal circuit for continuity
3. If the O2S 1 sensor signal circuit measures over the specified value, repair the open or poor connection as necessary.

Was an O2S 1 sensor signal circuit problem found and corrected?

5ohms

Go to Step 17

Go to Step 15

14 | Check the O2S 1 sensor low circuit terminal connection at the PCM and then replace the terminal if necessary. Did the terminal require replacement? | -- | Go to Step 17 | Go to Step 16
15 | Check the O2S 1 sensor signal circuit terminal connection at the PCM and replace the terminal if necessary. Did the terminal require replacement? | -- | Go to Step 17 | Go to Step 16
16 | Replace the PCM. Is the action complete? | -- | Go to Step 17 | --
17 |

1. Using the scan tool, clear the DTC's.
2. Start the engine and idle at normal operating temperature.
3. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

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

--

Go to Step 18

Go to Step 2

18 | Check if any additional DTC's are set. Are any DTC's displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK Refer to Diagnostic Aids