Circuit Description
The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust stream more quickly and accurately than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a signal voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant signal voltage. The ECM monitors the voltage variation on the signal circuit and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or reversing the direction of the current flow to the pumping cell. By measuring the direction and amount of current required to maintain the signal voltage, the ECM can determine the concentration of oxygen in the exhaust. The signal voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the system is lean, the oxygen level will be high and the lambda value will be high, or more than 1. When the system is rich, the oxygen level is low and the lambda value will be low, or less than 1. The ECM uses this information to maintain the proper air/fuel ratio. The ECM uses the forced lean or the forced rich condition of the catalyst diagnostic to simultaneously test the response time of the HO2S. If the ECM detects that the amplitude of the HO2S signal does not match an expected value, DTC P0133 will set for bank 1 sensor 1 or DTC P0153 will set for bank 2 sensor 1.
Conditions for Running the DTC
| • | DTCs P0021, P0024, P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0135, P0137, P0138, P0139, P0140, P0141, P0151, P0152, P0155, P0157, P0158, P0159, P0160, P0161, P0201-0208, P0221, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0279, P0280, P0282, P0283, P0300, P0301-0308, P0335, P0336, P0340, P0341, P0345, P0346, P0351-0358, P0365, P0366, P0390, P0391, P0442, P0443, P0446, P0449, P0453, P0454, P0455, P0458, P0459, P0496, P2231, P2234, P2237, P2240, P2243, P2247, P2251, P2254, P2626, P2629, P167A, P167B are not set. |
| • | The HO2S Loop Status parameter is Closed. |
| • | The BARO parameter is more than 74 kPa. |
| • | The Engine Speed parameter is between 1,216-3,000 RPM. |
| • | The MAF Sensor parameter is between 13-83 g/s. |
| • | The catalyst diagnostic is running. |
Conditions for Setting the DTC
The ECM detects that the amplitude of the HO2S signal does not match an expected value during the forced rich or forced lean portion of the catalyst diagnostic test.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Test Description
The number below refers to the step number of the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views | ||||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||||||||||||||
2 | If DTCs P0135, P0155, P2237, P2240, P2626, or P2629 are also set, diagnose those DTCs first. Are any of the above DTCs also set? | -- | Go to DTC P0135 or P0155 | Go to Step 3 | ||||||||||||||||||||
3 |
Does the lambda value reach the specified value as the engine decelerates? | 1.989 | Go to Step 4 | Go to Step 5 | ||||||||||||||||||||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||||||||||||||||||
5 |
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 5 | ||||||||||||||||||||
6 |
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 7 | ||||||||||||||||||||
7 |
Is the voltage less than the specified value? | 2.3 V | Go to Step 13 | Go to Step 8 | ||||||||||||||||||||
8 | Measure the voltage from the HO2S input pump current circuit, on the engine harness side connector, to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage within the specified range? | 2.8-3.1 V | Go to Step 14 | Go to Step 9 | ||||||||||||||||||||
9 | Is the voltage more than the specified value? | 3.1 V | Go to Step 15 | Go to Step 10 | ||||||||||||||||||||
Refer to Circuit Testing in Wiring Systems. Is the HO2S output pump current circuit voltage less than the specified value? | 10 mV | Go to Step 20 | Go to Step 11 | |||||||||||||||||||||
11 | With the jumper wire from the previous step still connected, observe the HO2S Bank 1 Sensor 1 or HO2S Bank 2 Sensor 1 parameter with a scan tool. Is the lambda value more than the specified value? | 1.060 | Go to Step 12 | Go to Step 16 | ||||||||||||||||||||
12 | Measure the resistance of the following circuits with a DMM:
Refer to Circuit Testing in Wiring Systems. Is the resistance of either circuit more than the specified value? | 5 ohms | Go to Step 21 | Go to Step 17 | ||||||||||||||||||||
13 | Test the HO2S low reference circuit for an open. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 19 | ||||||||||||||||||||
14 |
Important:
Test the HO2S reference voltage circuit for a short to the following circuits:
Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 19 | ||||||||||||||||||||
15 |
Important:
Test the HO2S low reference circuit for a short to the HO2S reference voltage circuit. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 19 | ||||||||||||||||||||
16 | Test the HO2S input pump current circuit for an open or high resistance. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 19 | ||||||||||||||||||||
17 | The HO2S may be detecting a lean or a rich exhaust condition. Inspect for one of the following conditions:
Repair any of the above or similar engine conditions as necessary. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 18 | ||||||||||||||||||||
18 | Test for poor connections and shorted terminals at the affected HO2S. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 22 | ||||||||||||||||||||
19 | Test for poor connections and shorted terminals at the ECM. 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 24 | Go to Step 23 | ||||||||||||||||||||
20 | Repair the short between the HO2S input pump current circuit and the HO2S output pump current circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||||||||||||||||
21 | Repair the circuit with high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||||||||||||||||
22 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||||||||||
23 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||||||||||
24 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 25 | ||||||||||||||||||||
25 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||||||||||||||||
