DTC P0133. Chevrolet Cavalier (CNG) 2001

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2001 🢒 Cavalier (CNG) 🢒 Engine 🢒 Engine Controls - 2.2L (LN2) 🢒 DTC P0133

Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

This DTC tests within the powertrain control module (PCM) and NOT within the Alternative Fuels Engine Control Unit (AF ECU).

The 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, P0506, P0507, P0601 are not set.

•	The engine is operating on alternative fuel.

•	The engine coolant temperature (ECT) is more than 75°C (167°F).

•	The engine speed is between 1600 RPM and 2200 RPM.

•	The engine is operating in closed loop.

•	The engine has been operating for at least 120 seconds with an engine speed of more than 450 RPM.

•	The throttle position (TP) angle is between 9 percent and 23 percent.

•	The throttle position (TP) angle changes less than 3 percent per second.

•	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 1174 mS for rich to lean sweeps, or 1008 mS for lean to rich sweeps.

The cycle time is more than 1491 mS.

Action Taken When the DTC Sets

•	The malfunction indicator lamp (MIL) will illuminate after 2 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.

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.

•	Use a scan tool in order to clear the DTCs.

Diagnostic Aids

DTC P0133 or slow response is most likely caused by one of the following conditions:

•

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 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.

O2S contamination is indicated if multiple response, switching, or time ratio O2S DTCs are set.

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.

Even small exhaust leaks can cause slow response from the O2S.

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 signal circuits or a short between the HIGH signal circuit and ground is indicated. With the O2S, AF ECU and the PCM disconnected the resistance between the HIGH and LOW signal circuits and the resistance between the HIGH signal circuit and ground should measure infinite.

If the voltage observed in step 8 is more than the range specified, a short between the HIGH signal 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, or an open, HIGH or LOW circuit is indicated.

Good circuit continuity measures less than 5 ohms with the AF ECU, 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

Did you perform the Diagnostic System Check-Engine Controls (Alternative Fuels)?

Go to Step 2

Go to Diagnostic System Check - Alternative Fuels (Engine Controls)

Start the engine.
Allow the engine to reach the normal operating temperature.
Operate the vehicle within the parameters specified under Conditions For Setting the DTC.
Monitor the Lean/Rich Avg. (mS), Rich/Lean Avg. (mS), and Rich/Lean to Lean/Rich Ratio on the O2S 1 using a scan tool.

Do the parameters show averages more than the Conditions For Setting the DTC?

Go to Step 4

Go to Step 3

Are any powertrain component DTCs set?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 5

The O2S sensor has been contaminated. Replace the affected O2S sensor. Refer to Heated Oxygen Sensor Replacement .
The contamination source must be removed prior to operating the engine with the replacement sensor. Possible sources of contamination include the following:

•	The use of a incorrect silicon RTV sealant

•	Engine coolant leakage into the combustion chamber

•	Excessive engine oil consumption

•	The use of silicon-contaminated fuel

•	The use of fuel containing LEAD

Did you complete the replacement?

Go to Step 14

Using the scan tool, store the DTC information from the PCM into the scan tool.
Clear the DTC Information from the PCM.
Communicate with the AF ECU and reset the fuel trim values.
Start and idle the engine until the normal operating temperature is reached.
Operate the engine under the Conditions for Running the DTC.

Did this DTC Run and Fail This Ignition?

Go to Step 7

Go to Step 6

This DTC is intermittent.

Are any additional DTCs stored?

Go to Diagnostic Trouble Code (DTC) List

Go to Diagnostic Aids

Check the exhaust system for leaks between the O2S and the engine.

Repair exhaust as necessary. Refer to Exhaust Leakage in Engine Exhaust.

Check the O2S and PCM connector for proper terminal contact.

Repair the connectors as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 8

Turn OFF the ignition.
Disconnect the O2S connector.
Turn ON the ignition.
Use a scan tool in order to monitor the O2S voltage for the sensor that applies to this DTC.

Does the O2S voltage measure within the value specified?

351-551 mV

Go to Step 9

Go to Step 11

Turn OFF the ignition.
Jumper the O2S High signal circuit to a ground.
Turn ON the ignition.
Use a scan tool in order to monitor the O2S voltage for the sensor that applies to this DTC.

Is the O2S voltage less than the value specified?

20 mV

Go to Step 10

Go to Step 12

Check for contamination sources that may have caused the O2S to fail.

O2S contamination sources include the following:

•	Use of an incorrect RTV silicon engine sealant

•	Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Excessive engine oil or coolant consumption

Repair or remove the source of the contamination.

Did you complete the repair?

Go to Step 13

Repair the short between the O2S HIGH and LOW signal circuits or between the O2S HIGH signal circuit and a voltage source. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

Check the O2S HIGH signal circuit and the O2S LOW signal circuit for an open or high circuit resistance.
Repair the O2S circuits as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

Replace the O2S. Refer to Heated Oxygen Sensor Replacement .

Did you complete the replacement?

Go to Step 14

Use the scan tool, in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 15

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK