| Table 1: | HO2S Voltages |
Circuit Description
The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information 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 powertrain control module (PCM) supplies a 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 PCM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The PCM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the PCM can determine the concentration of oxygen in the exhaust. The HO2S 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 fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The PCM uses this information to maintain the correct air/fuel ratio. The PCM monitors the HO2S for a transition from high to low and back to high. If the PCM determines the HO2S transition cycles take more than a predetermined amount of time, this DTC sets.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P0133 HO2S Slow Response Bank 1 Sensor 1 |
| • | DTC P0153 HO2S Slow Response Bank 2 Sensor 1 |
Conditions for Running the DTC
| • | Before the PCM can report that DTC P0133 or P0153 failed, DTC P0442 must run and pass. |
| • | DTCs P0030, P0050, P0107, P0108, P0112, P0113, P0117, P0118, P0135, P0155, P0171, P0172, P0300, P0301-P0306, P0335, P0401, P0403, P0404, P0443, P0496, P0501, P0641, P1128, P1129, P2227, P2228, P2229, P2297, P2413, P2414, P2415, P2646-P2649 are not set. |
| • | The engine coolant temperature (ECT) is more than 69°C (156°F). |
| • | The intake air temperature (IAT) is more than 0°C (32°F). |
| • | The engine speed is more than 1,050-2,000 RPM. |
| • | The manifold absolute pressure (MAP) is between 27-68 kPa. |
| • | The vehicle speed is more than 48 km/h (30 mph). |
| • | The HO2S lambda is between 0.73-1.47. |
| • | The engine is in Closed Loop. |
| • | The evaporative emission (EVAP) monitor is not running. |
| • | DTC P0133 and P0153 run once per drive cycle when the above conditions exist for more than 5 minutes. |
Conditions for Setting the DTC
The average transition time of the last 6 HO2S samples is more than 2.6 seconds.
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 OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Diagnostic Aids
| • | Use the J-35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | The Loop Status for the respective bank will default to Open when the DTC is current. |
| • | The wide band sensors do not toggle or switch like a switching HO2S. The HO2S signals will be relatively stable for an idling engine. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
| • | The following table illustrates the typical voltages for the HO2S circuits: |
| |||||
|---|---|---|---|---|---|
HO2S Circuit | Voltage | ||||
Heater Control | Less than 0.5 V | ||||
Heater Supply Voltage | B+ | ||||
Reference Voltage | 3.3-3.8 V | ||||
Low Reference | 5.9-6.4 V | ||||
Pump Current | 4.8-5.3 V | ||||
Input Pump Current | 3.3-3.8 V | ||||
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines whether a condition currently exists. If the Lambda value fluctuates near 1.00 and Loop Status is Closed, the HO2S is operating correctly.
-
This step determines if the fuel system is contaminated.
Step | Action | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | |||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||||||
|
Important:
Did DTC P0133 and/or DTC P0153 fail this ignition? | Go to Step 4 | Go to Step 3 | |||||||||
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Diagnostic Aids | ||||||||
Did DTC P0133 and DTC P0153 fail this ignition cycle? | Go to Step 7 | Go to Step 5 | |||||||||
5 | Inspect for an exhaust leak near the heated oxygen sensor (HO2S). Refer to Exhaust Leakage . After you inspect the exhaust system, return to this diagnostic. Did you find and correct the condition? | Go to Step 8 | Go to Step 6 | ||||||||
6 | Inspect or test for the following conditions:
Did you find and correct the condition? | Go to Step 8 | Go to Step 7 | ||||||||
7 |
Important: If both DTCs are set, determine and correct the cause of the contamination before replacing a sensor. Inspect for the following conditions:
Replace the HO2S. Refer to the appropriate procedure: Did you complete the replacement? | Go to Step 8 | -- | ||||||||
8 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 9 | ||||||||
9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |||||||||
