Circuit Description
The PCM continuously monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During the monitoring period the PCM counts the number of times that the a rich to lean and lean to rich response is indicated and adds the amount of time it took to complete all transitions. With this information, an average time for each transition can be determined. If the average response time is too slow, a DTC P0133 will be set. A lean to rich transition is indicated when the HO2S voltage changes from less than 300 mV to greater than 600 mV. A rich to lean transition is indicated when the HO2S voltage changes from more than 600 mV to less than 300 mV. An HO2S that responds too slowly is likely to be malfunctioning and should be replaced.
Conditions for Running the DTC
| • | No active fuel trim, fuel injector circuit, Misfire, EVAP, EGR, AIR, TP, IAT, MAP, ECT, CKP, or MAF sensor DTCs present. |
| • | P0131, P0132 or P0135 not set |
| • | System voltage is greater than 9 volts. |
| • | Closed Loop |
| • | Engine running for at least 3.3 minutes. |
| • | ECT greater than 75°C (167°F) |
| • | Engine speed between 1000 and 3000 RPM |
| • | MAF between 15 and 40 gm/s |
| • | Above conditions stable for 3 seconds |
Conditions for Setting the DTC
H02S 1 lean to rich average transition response time during the sample period was longer than 220 milliseconds or rich to lean average transition response time during the sample period was longer than 220 milliseconds.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns the MIL Off after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A last test failed (current DTC) clears when the diagnostic runs and does not fail. |
| • | A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures. |
| • | Use a scan tool in order to clear the MIL/DTC. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module (PCM) Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
• The PCM harness connectors • The electrical center fuse/relay cavities • The component terminals • The component harness connector
If the problem is intermittent, refer to Intermittent Conditions .
The heated oxygen sensors (HO2S) require an air reference for proper operation. The air reference is supplied through the HO2S wiring. Inspect the HO2S wires and connections for breaks or contamination. Do not use solder to repair HO2S wiring. Solder will obstruct the air path. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems for proper repair procedures.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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HO2S contamination may cause multiple HO2S DTCs to set.
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The use of leaded fuel may be indicated by the removal or tampering of the fuel filler restrictor.
An HO2S contaminated by silicon will have a white, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of silica contamination is the use of un-approved silicon RTV engine gasket material, the use of silicon based sprays or fluids within the engine or coolant consumption. Phosphorus contamination also leaves a white powdery coating on the HO2S. Phosphorus contamination comes from oil consumption. If the cause of this contamination is not corrected, the replacement HO2S will also get contaminated.
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Even small exhaust leaks can cause slow response from the HO2S.
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An HO2S contaminated by silicon will have a white, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of silica contamination is the use of un-approved silicon RTV engine gasket material, the use of silicon based sprays or fluids within the engine or coolant consumption. Phosphorus contamination also leaves a white powdery coating on the HO2S. Phosphorus contamination comes from oil consumption. If the cause of this contamination is not corrected, the replacement HO2S will also get contaminated.
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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 HO2S 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 greater than the range specified a short between the High circuit and an ignition voltage source is indicated.
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If the voltage observed in Step 9 is not below 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 HO2S connector. Ensure PCM terminal contact is good.
Step | Action | Value(s) | Yes | No | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||||||||||||||||||||||||
2 | Is DTC P0140 also set? | -- | ||||||||||||||||||||||||||||||||
3 | Are any powertrain component DTC's set? | -- | Go to the applicable DTCs | |||||||||||||||||||||||||||||||
4 |
Has the contamination source been removed and the affected sensors replaced? | -- | -- | |||||||||||||||||||||||||||||||
5 |
Did this DTC run and fail this ignition? | -- | ||||||||||||||||||||||||||||||||
6 | The condition that set this DTC is not present. This DTC may have been set by one of the following conditions:
Repair any of the above or similar engine conditions as necessary. Was a condition found and repaired? | -- | Refer to Diagnostic Aids | |||||||||||||||||||||||||||||||
7 |
Repair exhaust as necessary. Repair terminal contact as necessary. Was a repair made? | -- | ||||||||||||||||||||||||||||||||
8 |
Is the HO2S voltage within the value range specified? | 351 to 551 mV | ||||||||||||||||||||||||||||||||
9 |
Is the HO2S voltage less than the value specified? | 20 mV | ||||||||||||||||||||||||||||||||
10 |
Does the test lamp illuminate? | -- | ||||||||||||||||||||||||||||||||
11 | Connect the test lamp between the HO2S heater ignition feed circuit terminal and the HO2S heater ground circuit terminal (both, engine harness side). Does the test lamp illuminate? | -- | ||||||||||||||||||||||||||||||||
12 |
HO2S contamination sources include the following:
Is the action complete? | -- | -- | |||||||||||||||||||||||||||||||
13 |
Is the action complete? | -- | -- | |||||||||||||||||||||||||||||||
14 |
Is the action complete? | -- | -- | |||||||||||||||||||||||||||||||
15 | Repair the HO2S Heater ignition feed circuit. Is the action complete? | -- | -- | |||||||||||||||||||||||||||||||
16 | Repair the HO2S Heater ground circuit. Is the action complete? | -- | -- | |||||||||||||||||||||||||||||||
17 | Replace the HO2S. Refer to Heated Oxygen Sensor Replacement . Is the action complete? | -- | -- | |||||||||||||||||||||||||||||||
18 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||||||||||||||||||||||||||||
19 | Review Captured Info using the scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
