Circuit Description
The PCM continuously monitors the oxygen sensor (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 and adds the amount of time that the O2S 1 took in order to complete all of the switches. With this information, you can determine an average time for all of the switches. If the average time to switch is too slow, a diagnostic trouble code (DTC) P0133 will set.
Conditions For Running The DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0301, P0302, P0303, P0304, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 are not set. |
| • | Fuel level is greater than 10 percent. |
| • | Engine coolant temperature (ECT) is more than 70°C (158°F). |
| • | Engine speed is between 1,600 RPM and 2,450 RPM. |
| • | Engine is operating in closed loop. |
| • | Throttle position (TP) angle is between 9 percent and 18 percent. |
| • | Evaporative emissions control system is commanded OPEN for more than 36 percent. |
| • | Purge learned memory is more than approximately 0.78. |
| • | 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 more than 1119 mS for rich to lean sweeps or 760 mS for lean to rich sweeps.
Or
Sum of rich to lean and lean to rich is greater than 1235 mS.
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/Failure Records buffers. |
| • | A history DTC stores. |
| • | The coolant fan turns ON. |
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. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
DTC P0133 or slow response is most likely caused by one of the following items:
| • | Fuel pressure--The system will go rich if fuel pressure is too high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0172 may set. Refer to the DTC P0172 . |
| • | Leaking injector--A leaking or malfunctioning injector can cause the system to go rich. |
| • | 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 MAP 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 fuel pressure regulator. |
| • | TP sensor--An intermittent TP sensor output can cause the system to go rich due to a false indication of the engine accelerating. |
| • | O2S 1 contamination--Inspect the O2S 1 for silicone contamination from fuel or the use of improper room temperature vulcanizing (RTV) sealant. The O2S 1 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:
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O2S contamination is indicated if multiple response, switching, or time ratio O2S DTCs are set.
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An O2S contaminated by silicon will have a white, powdery deposit on the portion of the O2S that is exposed to the exhaust stream. The usual cause of silica contamination is the use of an unapproved 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 O2S will also become contaminated.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
|
Important: If any other DTCs are set (except HO2S DTCs), refer to other DTCs first before proceeding with this table.
Does scan tool indicate O2 voltage varying outside the specified values? | 400-500 mV | Go to Step 3 | Go to Step 4 | |||||||
3 | Operate vehicle within Failure Records conditions. Does the scan tool indicate this DTC failed this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||
4 | Inspect and test for the following:
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 5 | ||||||
5 |
Does the voltage measure within the specified value? | 351-551 mV | Go to Step 6 | Go to Step 8 | ||||||
6 |
Does the scan tool indicate O2 voltage at or near the specified value? | 0 mV | Go to Step 9 | Go to Step 7 | ||||||
7 | Test the low signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 | ||||||
8 | Test the high signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 | ||||||
9 | Test for poor connections at the O2S. 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 13 | Go to Step 10 | ||||||
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Important: Determine the cause of contamination before replacing the sensor. Inspect and test for the following:
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 O2S sensor. Refer to Oxygen Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | |||||||
11 | 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 13 | Go to Step 12 | ||||||
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 | ||||||
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||
