P0133
DTC P0133 O2S Slow Response 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. Then adds the amount of time that the O2S 1 took to complete all the switches. With this information, an average time for all switches can be determined. Whenever the average time to switch is too slow, a DTC P0133 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 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 time is greater than 6.0 or less than 0.
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 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
- A scan tool can clear the DTCs
Diagnostic Aids
DTC P0133 or slow response is most likely caused by one of the following:
- The fuel pressure The system will go rich if the fuel pressure is to high. The PCM can compensate for some increase, if the fuel pressure gets too high, a DTC P0172 may set. Refer to Fuel System Diagnosis.
- A leaking fuel injector - A leaking or faulty fuel 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.
- The O2S 1 contamination Inspect the 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.
Steps 1 - 2:
Steps 3 - 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 the technician to complete some of the 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 malfunction occurred. The information then stores in the scan tool for later reference.
16. Reprogram the replacement PCMs and perform the crankshaft position system variation procedure. Refer to the latest Isuzu Technical Communications System (ITCS) information for PCM programming and the CKP System Variation Learn Procedure for the crankshaft position system variation learn procedure.
18. If no malfunctions have been found at this point and no additional DTCs were set, refer to the Diagnostic Aids for additional checks and information.