Circuit Description
The powertrain control module (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
| • | No active MAP DTCs |
| • | No active IAT DTCs |
| • | No active ECT DTCs |
| • | No active TP DTCs |
| • | No active fuel trim DTCs |
| • | No active injector control DTCs |
| • | No active misfire DTCs |
| • | No active CKP DTCs |
| • | No active EVAP DTCs |
| • | No active IAC DTCs |
| • | No active PCM memory DTCs |
| • | ECT is more than 75°C (167°F) |
| • | Engine speed is between 1600 RPM and 2,600 RPM |
| • | Engine is operating in Closed Loop |
| • | Throttle position (TP) angle is between 14 percent and 26 percent |
| • | Evaporative emissions control system is commanded open for more than 40 percent |
| • | Purge learned memory is more than 191 |
| • | The engine run time is more than 10 seconds |
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
Ratio of response times is more than 4.25 or less than 0.44.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles. |
| • | The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tools Freeze Frame and Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
DTC P0133 or slow response is most likely caused by one of the following conditions:
| • | The fuel pressure -- The system will go rich if the fuel pressure is too high. The PCM can compensate for some increase. If the fuel pressure gets too high, a DTC P0132 and P0172 may also set. Refer to Fuel System Diagnosis . |
| • | A leaking fuel injector -- A leaking or faulty fuel 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 (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. |
| • | 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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
When the system is operating correctly the O2S voltage should toggle above and below the specified values.
-
The specified value is what is measured on a correctly operating system.
-
The specified value is what is measured on a correctly operating system.
-
The replacement PCM must be reprogrammed and the Crankshaft Position System Variation Learn procedure must be preformed.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
|
Important:: If any other DTCs are set, refer to the other DTCs before proceeding with this table.
Does the O2S 1 voltage read outside the specified range? | 400-500 mV | |||||||||
3 | Operate vehicle within the Failure Records conditions. Does the DTC reset? | -- | Go to Diagnostic Aids | |||||||
4 | Inspect and test for the following conditions:
Did you find and correct the condition? | -- | ||||||||
Does the O2S 1 voltage measure near the specified value? | 450 mV | |||||||||
Does the O2S 1 voltage measure near the specified value? | 0 mV | |||||||||
7 |
Did you find and correct the condition? | -- | ||||||||
8 |
Did you find and correct the condition? | -- | ||||||||
9 |
Did you find and correct the condition? | -- | ||||||||
10 |
Important:: Determine the cause of contamination before replacing the sensor. Inspect and test for the following conditions:
Replace the O2S 1. Refer to Oxygen Sensor Replacement . Did you complete the replacement? | -- | -- | |||||||
11 |
Did you find and correct the condition? | -- | ||||||||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||||
13 |
Does the DTC reset? | -- | System OK |
