P0133
DTC P0133 O2S Slow Response Sensor 1
Circuit Description
The PCM monitors the Oxygen Sensor 1(O2S 1) activity continuously for 100 seconds. During the monitoring period, the PCM counts the number of times that the O2S 1 switches from rich to lean and from lean to rich. The PCM then determines the amount of time that the O2S 1 took to complete all of the switches. Using this information, the PCM can calculate the average time taken for each switch. Whenever the average time taken to switch is too slow, a DTC P0133 will set.
Conditions for Running the DTC
- There are no active manifold absolute pressure (MAP) DTCs.
- There are no active intake air temperature (IAT) DTCs.
- There are no active engine coolant temperature (ECT) DTCs.
- There are no active throttle position (TP) DTCs.
- There are no active fuel trim DTCs.
- There are no active injector control DTCs.
- There are no active misfire DTCs
- There are no active crankshaft position (CKP) DTCs.
- There are no active evaporative emissions (EVAP) DTCs.
- There are no active idle air control (IAC) DTCs.
- The engine coolant temperature (ECT) is more than 75° C (167° F).
- The engine speed is between 1600 - 2600 RPM.
- The engine is operating in closed loop.
- The throttle position (TP) angle is between 14 - 26 percent.
- The evaporative emissions control system is commanded open for more than 40 percent.
- The purge learned memory is more than approximately 0.86.
- The above conditions have been present for a total of 30 seconds accumulated time.
Conditions for Setting the DTC
The average O2S 1 response times are more than 249 mS for rich to lean sweeps or 249 mS for lean to rich sweeps.
Or
The ratio of response times is more than 6.0 or less than 0.2.
Action Taken When the DTC Sets
- The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive ignition cycles.
- The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is recorded in the scan tool's Freeze Frame and Failure Records.
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.
- The DTCs can be cleared using the scan tool Clear Information function.
Diagnostic Aids
DTC P0133 or slow response is most likely caused by one of the following conditions:
- Incorrect fuel pressure The system will go rich if the fuel pressure is too high. The PCM can compensate for some increase in pressure, but 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 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 cause the PCM to substitute a default value for the MAP sensor output. If the rich condition disappears when the MAP sensor is disconnected, substitute a known good sensor and check the system again.
- 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.
- Possible O2S 1 contamination-Inspect the O2S 1 for silicon contamination from fuel or from the use of an incorrect RTV sealant. Inspect the O2S 1 for a white powdery coating. Contamination of the O2S may result in a high, but false, voltage signal, which will be interpreted by the PCM as a rich exhaust. The PCM will then reduce the amount of fuel delivered to the engine, which can cause a severe surge or driveability problem.
Step 1:
Steps 2 - 4:
Steps 5 - 8:
Steps 9 - 11:
Steps 12 - 15:
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
2. HO2S contamination is indicated if multiple Response, Switching or Time Ratio HO2S DTCs are set.
4. The use of leaded fuel may be indicated by the removal or tampering of the fuel filler restrictor.
An HO2S contaminated by silicon will have a white, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of silica contamination is the use of un-approved silicon RTV engine gasket material or the use of silicon based sprays or fluids within the engine.
If the cause of this contamination is not corrected, the replacement HO2S will also get contaminated.
7. Even small exhaust leaks can cause slow response from the HO2S.
12. An HO2S contaminated by silicon will have a white, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of silica contamination is the use of un-approved silicon RTV engine gasket material or the use of the use of silicon based sprays or fluids within the engine. If the cause of this contamination is not corrected the replacement HO2S will also get contaminated.
13. If the voltage observed in step 8 is less than the range specified a short between the HIGH and LOW circuits or a short between the HIGH circuit and ground is indicated. With the HO2S and the PCM disconnected the resistance between the HIGH and LOW circuits and the resistance between the HIGH circuit and ground should measure infinite.
If the voltage observed in step 8 is more than the range specified a short between the HIGH circuit and an ignition voltage source is indicated.
14. If the voltage observed in step 9 is not below the voltage specified a high resistance (open) HIGH or LOW circuit is indicated.
Good circuit continuity measures less than 5 ohms with the PCM and sensor disconnected. Measure between the PCM connector and the HO2S connector. Ensure PCM terminal contact is good.