Circuit Description
The Powertrain Control Module (PCM) continuously monitors the oxygen sensor 1 (O2S 1) activity 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, then adds the 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, P0201, P0202, P0203, P0204, P0300, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 are not set. |
| • | The engine coolant temperature (ECT) is more than 75°C (167°F). |
| • | The engine speed is between 1800 RPM and 2300 RPM. |
| • | The engine is operating in closed loop. |
| • | The throttle position (TP) angle is between 8 percent and 15 percent. |
| • | The evaporative emissions control system is commanded open for more than 80 percent. |
| • | The purge learned memory is more than approximately 0.86. |
| • | The diagnostic completes when 30 seconds of accumulated time has been spent in the above conditions. |
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 6.0 or less than 0.2.
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. |
| • | 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:
| • | The fuel pressure -- The system will go rich if the fuel pressure is too high. The PCM can compensate for some increase, but if the fuel pressure becomes too high, a DTC P0172 may set. Refer to the Fuel System Diagnosis . |
| • | A leaking injector -- A leaking or malfunctioning 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, or a 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. |
| • | The pressure regulator -- Check for a leaking fuel pressure regulator diaphragm by confirming the presence of liquid fuel in the vacuum line to the fuel pressure regulator. |
| • | The throttle position (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 from the use of an improper room-temperature vulcanizing (RTV) sealant. The O2S 1 sensor may have a white powdery coating which will result in a high but false voltage signal, indicating a rich exhaust. 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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The use of leaded fuel may be indicated by evidence of the removal or tampering of the fuel filter restrictor.
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 room-temperature vulcanizing (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 O2S will also become contaminated.
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Even small exhaust leaks can cause slow response from the O2S.
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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.
-
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 O2S 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.
-
If the voltage observed in step 9 is not less than 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 O2S connector. Ensure that the PCM terminal contact is good.
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||||
Do the parameters show averages more than the specified value? | 249 ms | |||||||||||||
3 | Are any powertrain component DTCs set? | -- | ||||||||||||
Has the contamination source been removed and the affected sensor replaced? | -- | -- | ||||||||||||
5 |
| -- | ||||||||||||
6 | This DTC is intermittent. Are any additional DTCs stored? | -- | Go to Diagnostic Aids | |||||||||||
Repair exhaust as necessary. Refer to Exhaust Leakage - Not OBD II in Engine Exhaust. Repair the connectors as necessary. Refer to Connector Repairs in Wiring Systems. Did you find a problem? | -- | |||||||||||||
8 |
Is the O2S voltage within the value specified? | 351-551mv | ||||||||||||
9 |
Is the O2S voltage less than the value specified? | 20mv | ||||||||||||
10 |
O2S contamination sources include the following:
Is the action complete? | -- | -- | |||||||||||
11 | Repair the short between the O2S HIGH and LOW circuits or between the O2S HIGH signal circuit and a voltage source. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||||
Is the action complete? | -- | -- | ||||||||||||
Replace the O2S. Refer to Oxygen Sensor Replacement . Is the action complete? | -- | -- | ||||||||||||
Does the scan tool indicate the diagnostic Passed? | -- | |||||||||||||
15 | Does the scan tool display any additional undiagnosed DTCs? | -- | System OK |
