For 1990-2009 cars

### Circuit Description

The PCM continuously monitors the oxygen sensor 1 (O2S 1) activity for 100 seconds. During the monitoring period, the PCM counts the times that the O2S 1 switches from rich to lean and from lean to rich. You can determine a total for all of the switches with this information. If the number of switches is too low, a DTC P1133 will set.

### Conditions For Running The DTC

• | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0301, P0302, P0303, P0304, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 are not set.

• | The fuel level is greater than 10 percent.

• | The engine coolant temperature (ECT) is more than 70°C (158°F).

• | The engine speed is between 1,600-2,450 RPM.

• | The engine is operating in closed loop.

• | The throttle position (TP) angle is between 9-18 percent.

• | The evaporative emissions control system is commanded open for more than 36 percent.

• | The purge learned memory is more than approximately 0.78.

• | 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 2 or the lean to rich counts is less than 2.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Diagnostic Aids

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

• | The fuel pressure--The system will go rich if fuel pressure is too high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0172 will be set. Refer to Fuel System Diagnosis .

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

• | The 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.

• | The 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.

• | The TP sensor--An intermittent TP sensor output will 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, indicating a rich exhaust. 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 the 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 | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 |

1. Turn ON the ignition, with the engine OFF.
2. Install a scan tool.

Are any component DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3 |

1. Start the engine.
2. Idle the engine at the normal operating temperature.
3. Operate the vehicle within the Conditions for Running this DTC.

Does the scan tool indicate that the DTC failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn OFF the ignition.
2. Inspect the following conditions:

• | Inspect to see that the O2S 1 is securely installed.

• | Inspect for corrosion on the terminals.

• | Inspect for terminal tension at the following connections:

- | The O2S 1 electrical connector

- | The PCM electrical connector

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

• | Inspect for any damaged wiring.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 5

5 |

1. Start the engine.

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

2. Inspect the exhaust manifold for an exhaust leak near the engine
3. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 6

6 |

1. Turn OFF the ignition.
2. Disconnect the O2S sensor.
3. Jumper the O2S low signal circuit to a good ground.
4. Turn ON the ignition, with the engine OFF.
5. Measure the voltage on the O2S high signal circuit on the PCM side, using a DMM that is connected to a good ground.

Does the voltage measure within the specified value?

351-551 mV

Go to Step 7

Go to Step 11

7 | Connect a jumper wire between the O2S 1 high signal circuit, on the PCM side of the high signal circuit to a ground. Does the scan tool voltage indicate that the O2S 1 voltage is below the specified value? | 20 mV | Go to Step 8 | Go to Step 12
8 | Inspect for poor connections at the harness connector of the O2S sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 9
9 |

1. Turn OFF the ignition.

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 .

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

• | Fuel contamination

• | Use of improper an RTV sealant

• | Engine oil/coolant consumption

Did you complete the replacement?

--

Go to Step 18

--

10 | Repair the condition as necessary. Did you complete repair? | -- | Go to Step 18 | --
11 |

1. Turn OFF the ignition.
2. Test the O2S 1 high signal circuit for a short to ground or an open. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

12 |

1. Remove the jumper wire.
2. Measure the voltage between the O2S 1 high signal circuit and ground using a DMM.

Does the O2S 1 voltage measure above the specified value?

407 mV

Go to Step 13

Go to Step 14

13 |

1. Turn OFF the ignition.
2. Disconnect the PCM electrical connectors.
3. Test the O2S 1 low signal circuit for continuity.
4. If the O2S 1 low signal circuit measures over the specified value, repair the following conditions:

• | An open circuit

• | A faulty connector

Did you find and correct the condition?

5 ohms

Go to Step 18

Go to Step 15

14 |

1. Turn OFF the ignition.
2. Disconnect the PCM electrical connectors.
3. Test the O2S 1 high signal circuit for continuity.
4. If the O2S 1 low signal circuit measures over the specified value , repair the following conditions:

• | An open circuit

• | A faulty electrical terminal connection

Did you find and correct the condition?

5 ohms

Go to Step 18

Go to Step 16

15 |

1. Inspect the O2S 1 low signal circuit for a poor connection at the PCM.
2. If you find a problem, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

16 |

1. Inspect the O2S 1 high signal circuit for a poor connection at the PCM.
2. If you find a problem, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

17 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | --
18 |

1. Use a scan tool in order to clear the DTCs.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 19

Go to Step 2

19 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List | System OK