The oxygen sensors (O2S) is used for fuel control and catalyst monitoring. The O2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the O2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the O2S with a reference, or bias voltage of about 450 mV. While the engine runs, the O2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient O2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the O2S voltage to determine the air-to-fuel ratio. An O2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An O2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.
The O2S utilizes the following circuits:
• | A signal circuit |
• | A low reference circuit |
The ECM monitors the rich-to-lean and lean-to-rich response time. A response time is defined as the HO2S voltage changes from above 600 mV to below 300 mV or from below 300 mV to above 600 mV. If the ECM detects that the response time is too long, this DTC sets.
This diagnostic procedure supports the following DTC:
DTC P0133 O2S Slow Response Sensor 1
• | DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0137, P0138, P0300, P0335, P0336, P0341, P0400, P0404, P0405, P0444, and P0445 are not set. |
• | The engine coolant temperature is more than 60°C (140°F). |
• | The ignition 1 voltage is more than 10 volts. |
• | The fuel system is in closed loop. |
• | The engine speed is between 1,800-2,900 RPM. |
• | The vehicle speed is between 45-55 km/h (28-34 mph). |
• | The mass air flow (MAF) is between 60-160 mg/tdc. |
• | The manifold air pressure (MAP) is more than 70 kPa. |
• | The DTC runs continuously once the above conditions are met. |
The ECM detects that the HO2S rich-to-lean average response time or lean-to-rich average response time is more than 3 times the normal transition time for 10-20 minutes depending on engine load and speed.
Or
The ECM detects that the HO2S signal spends more time in the rich region as compared to the lean region or the HO2S signal spends more time in the lean region as compared to the rich region for 10-20 minutes depending engine load and speed.
• | The malfunction indicator lamp (MIL) will illuminate. |
• | The coolant fan turns ON. |
• | The vehicle will operate in Open Loop. |
• | The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault. |
• | DTCs can be cleared by using the scan tool. |
• | Disconnect the ECM battery feed for 10 seconds. |
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the condition is present. This test may take 5-10 minutes for the diagnostic to run.
An exhaust leak 6-12 inches away from the O2S can cause a DTC to set.
Certain RTV silicone gasket materials release vapors that can contaminate the O2S. Silicone in the fuel can also cause silicone contamination. If the sensors appear contaminated by silicone, and if all the silicone sealant is a non-silicone base, advise the customer to try a different fuel company. A missing fuel filler restrictor indicates that the customer may have used leaded fuel.
Step | Action | Yes | No | ||||||||||||||||
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Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||||||||||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | |||||||||||||||||
Important: If any other DTCs are set, refer to those DTCs before proceeding with this diagnostic table.
Does the DTC fail this ignition? | Go to Step 4 | Go to Step 3 | |||||||||||||||||
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Intermittent Conditions | ||||||||||||||||
Inspect for an exhaust leak near the O2S. After you inspect the exhaust system, return to this diagnostic. Did you find and correct the condition? | Go to Step 7 | Go to Step 5 | |||||||||||||||||
Inspect or test for the following conditions:
Did you find and correct the condition? | Go to Step 7 | Go to Step 6 | |||||||||||||||||
6 | Replace the O2S. Refer to Oxygen Sensor Replacement . Did you complete the replacement? | Go to Step 7 | -- | ||||||||||||||||
7 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 8 | ||||||||||||||||
8 | Are there any DTCs that have not been diagnosed? | System OK |