Circuit Description
The powertrain control module (PCM) continuously monitors the heated oxygen sensor 1 (HO2S 1) activity for 100 seconds. During the monitoring period, the PCM counts the number of times that the HO2S 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, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0336, P0440, P0446, P0452, P0453, P0507, P0601, P0602, P0604, P0606, P1120, P1220, P1221, P1271, P1275, P1280, P1484, P1512, P1514, P1515, P1516, P1621, P1635, P1639, P1680, or P1681 are not set. |
| • | The fuel level sensor is more than 10 percent. |
| • | The engine coolant temperature (ECT) is more than 70°C (158°F). |
| • | The engine speed is between 1,450-1,900 RPM. |
| • | The engine has been running for more than 200 seconds. |
| • | The loop status is closed. |
| • | The throttle position (TP) indicated angle is between 25-30 percent. |
| • | The evaporative emission (EVAP) purge solenoid command is more than 10 percent. |
| • | The above conditions have been met for 30 seconds. |
Conditions for Setting the DTC
The HO2S 1 rich to lean counts is less than 2 or lean to rich counts is less than 2.
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/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 in order to clear the DTCs. |
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. If the fuel pressure 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 manifold absolute pressure (MAP) sensor--An output that causes the PCM to sense a higher than normal manifold pressure, indicating a 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 throttle position (TP) sensor--An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating. |
| • | HO2S 1 contamination--Inspect HO2S 1 for silicone contamination from fuel or from the use of an incorrect RTV sealant. The sensor may have a white powdery coating. This condition can 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. |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Important: If any other DTCs are set, except HO2S DTCs, refer to other DTCs first before proceeding with this table.
Does the DTC fail this ignition? | -- | Go to Step 3 | |||||||
3 | Inspect and test for the following conditions:
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 4 | ||||||
4 |
Does the voltage measure near the specified value? | 450 mV | Go to Step 5 | Go to Step 7 | ||||||
5 |
Does the scan tool indicate HO2S voltage at or near the specified value? | 0 mV | Go to Step 8 | Go to Step 6 | ||||||
6 | Test the HO2S low signal circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||
7 | Test the HO2S high signal circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||
8 | Test for poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||
9 |
Important: Determine the cause of contamination before replacing the sensor. Inspect and test for the following conditions:
Notice: Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.
Replace the HO2S. Refer to Heated Oxygen Sensor 1 Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
10 | Test for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 | ||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
12 |
Does the DTC run and pass? | -- | Go to Step 13 | Go to Step 2 | ||||||
13 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||
