For 1990-2009 cars
Engine Controls Components
Power, Ground, HO2S 2, and O2S 1
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

### Circuit Description

The Powertrain Control Module (PCM) continuously monitors the oxygen sensor 1 (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. If the number of switches is too low, a DTC P1133 will set.

### Conditions For Running The DTC

• | The following DTCs are not set: P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441.

• | The engine coolant temperature (ECT) is more than 75°C (167°F).

• | The engine speed is between 1800 and 2300 RPM.

• | The engine operating in closed loop.

• | The throttle position (TP) angle is between 8 percent and 15 percent.

• | The evaporative emissions (EVAP) control system is commanded open for more than 80 percent.

• | The purge learned memory is more than approximately 0.86.

• | The diagnostic completes when 30 seconds of accumulated time has been spent in the above conditions.

### Conditions for Setting the DTC

The number of rich to lean counts is less than 1 or the lean to rich counts is less than 1.

### 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 stores.

### 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.

• | Use a scan tool to clear the DTCs.

### Diagnostic Aids

DTC P1133 is most likely caused by one of the following conditions:

• | The fuel system will go rich if the fuel pressure is too high. The PCM can compensate for some increase. If the fuel pressure becomes too high, a DTC P0132 will be set. Refer to Fuel System Diagnosis .

• | A leaking or malfunctioning fuel injector can cause the system to go rich.

• | A manifold absolute pressure (MAP) 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 disappears while the sensor is disconnected.

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

• | Inspect the O2S 1 for silicone contamination from fuel or use of improper RTV sealant. The sensor may have a white powdery coating which results 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

The number below refers to step number on the diagnostic table.

1. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

#### DTC P1133-Oxygen Sensor (O2S) Insufficient Switching (Sensor 1)

Step | Action | Values | 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. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
2. Use a scan tool in order to observe the Lean/Rich and Rich/Lean Transitions.

Do the transitions read less than the specified values?

1-1

Go to Step 3

Go to Diagnostic Aids

3 |

1. Turn off the ignition.
2. Verify that the O2S 1 is securely installed.
3. Inspect for damaged wiring.
4. Inspect for poor connections of the O2S 1 circuits at the following locations:

• | The O2S 1 connector

• | The PCM connector

5. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct any of these conditions?

--

Go to Step 13

Go to Step 4

4 |

1. Reinstall any connectors if removed.
2. Start the engine and idle the engine.

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

3. Inspect the exhaust system for a leak near the engine.
4. If a problem is found, repair as necessary.

Did you find and correct a condition?

--

Go to Step 13

Go to Step 5

5 |

1. Turn off the ignition.
2. Disconnect the O2S 1 connector.
3. Turn on the ignition, leaving the engine off.
4. Use a scan tool in order to observe the O2S 1 voltage.

Is the voltage within the specified range?

407-509 mV

Go to Step 6

Go to Step 8

6 | Connect a jumper wire between the O2S 1 signal circuit and ground at the connector. Is the voltage less than the specified value? | 200 mV | Go to Step 7 | Go to Step 9
7 |

1. Turn off the ignition.

Notice: Determine and correct the cause of the contamination in order to prevent damage to the replacement sensors.

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

2. Replace the O2S 1. Refer to Oxygen Sensor Replacement .

Did you complete the repair?

Go to Step 13

--

8 |

1. Turn off the ignition.
2. Repair a short to ground in the O2S 1 signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

9 |

1. Remove the jumper wire.
2. Use the DMM in order to measure the voltage between the O2S 1 signal circuit and ground.

Is voltage more than the specified value?

407 mV

Go to Step 10

Go to Step 11

10 |

1. Turn off the ignition.
2. Disconnect the PCM connectors.
3. Use the DMM in order to test the O2S 1 low circuit for continuity.
4. If the DMM reads over the specified value, repair the following conditions:

• | An open circuit

• | A poor connection

Did you find and correct the condition?

5 ohms

Go to Step 13

Go to Step 12

11 |

1. Turn off the ignition.
2. Disconnect the PCM connectors.
3. Use the DMM in order to test the O2S 1 signal circuit for continuity.
4. If the resistance is more than the specified value, repair the following conditions:

• | An open circuit

• | A poor connection

Did you find and correct the condition?

5 ohms

Go to Step 13

Go to Step 12

12 | Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the repair? | -- | Go to Step 13 | --
13 |

1. Use a scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running this DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK