P1133
DTC P1133 O2S Insufficient Switching Sensor1
Circuit Description
The 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. 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, P0200, P0300, P0301, P0302, P0303, P0304, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 not set.
- ECT is greater than 75 °C (167 °F).
- Engine speed is between 1800 RPM and 2300 RPM.
- Engine is operating in closed loop.
- Throttle Position (TP) angle is between 8% and 15%.
- Evaporative emissions control system is commanded open for greater than 80%.
- Purge learned memory is greater than approximately 0.86.
- Diagnostic completes when 30 seconds 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 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.
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 P1133 is most likely caused by one of the following:
- 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 P0172 will be set. Refer to Fuel System Diagnosis.
- Leaking injector - A leaking or malfunctioning 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 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 (rich exhaust indication). The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem.
Step 1:
Steps 2 - 4:
Steps 5 - 7:
Steps 8 - 11:
Steps 12 - 15:
Steps 16 - 18:
Test Description
The number(s) below refer(s) to the step number(s) 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 captured when this DTC set. The scan tool stores this data for later reference.
16. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Isuzu Technical Communication System (ITCS) procedures for PCM reprogramming and the CKP System Variation Learn Procedure for the crankshaft position system variation learn procedure.
18. If no malfunctions are present at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.