Circuit Description
Important: If the voltage is measured with a 10 Megaohm Digital Voltmeter, the voltage may read as low as 0.32 volt (320 mV).
The VCM supplies a voltage of about 0.45 volt (450 mV) between the HO2S Signal and HO2S Low circuits. The Heated Oxygen Sensor varies the voltage within the range of about 1.0 volt (1000 mV) if the exhaust is rich, down to about 0.10 volt (100 mV) if the exhaust is lean. This is a type A DTC.
The sensor is like an open circuit and produces no voltage when it is below 360°C (600°F). The DTC P0131, P0132, an open signal circuit, or a cold sensor causes Open Loop operation. The DTC P0131 determines if the HO2S sensor or the signal circuit is shorted to low by checking for a lean condition during a steady throttle and power enrichment (PE).
Conditions for Setting the DTC
| • | No TP sensor DTCs |
| • | No EVAP DTCs |
| • | No IAT sensor DTCs |
| • | No MAP sensor DTCs |
| • | No ECT sensor DTCs |
| • | No MAF sensor DTCs |
| • | No intrusive test in progress |
| • | No device controls active |
| • | The system voltage measures at least 9.0 volts |
Test Enable (Rich Test)
| • | Closed Loop |
| • | Air to fuel ratio is at least 14.5 but less than 14.8 |
| • | The TP is greater than 0% but less than 50% |
| • | The above must be met for 5 seconds |
| • | HO2S (Bank 1, Sensor1) DTCs not active since code clear |
| • | The HO2S (Bank 1, Bank 1) voltage measures greater than 0.976 volts (976 mV) |
Test Enable (DFCO Rich Test)
| • | Decel Fuel cutoff mode is active |
| • | Closed Loop |
| • | The time elapsed is at least 2 seconds |
| • | HO2S (Bank 1, Sensor 1) DTCs not active since code clear |
| • | The HO2S (Bank 1, Sensor 1) voltage measures greater than 0.468 volts (486 mV) |
Action Taken When the DTC Sets
A current DTC P0132 causes the system to operate in the Open Loop. With a current DTC P0132 set, the MIL turns ON after 1 test failure.
Conditions for Clearing the MIL or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order to clear the DTCs. |
Diagnostic Aids
Check the following items:
| • | The fuel pressure: If the pressure is too high, the system will run rich. The VCM can compensate for some increase; however, if the pressure gets too high, the DTC P0132 may set. Refer to Fuel System Diagnosis . |
| • | A rich injector. Perform an Injector Balance test. Refer to Fuel Injector Balance Test for the 5.0L, 5.7L or the 7.4L. |
| • | Fuel contaminated oil |
| • | EVAP canister purge: Check for a fuel saturation. If full of fuel, check the canister control and hoses. Refer to Fuel System Cleaning . |
| • | Leaking fuel pressure regulator diaphragm by checking the vacuum line to the regulator for fuel. |
| • | The TP sensor: An intermittent TP sensor output causes the system to run rich due to a false indication of the throttle moving. |
| • | False rich indication due to silicon contamination of the heated oxygen sensor. A DTC P0132 accompanied by a lean driveability conditions and a powdery white deposit on the sensor indicates a false rich indication. |
| • | Faulty HO2S (Bank 1, Sensor 1): the HO2S (Bank 1, Sensor 1) is internally shorted, the HO2S (Bank 1, Sensor 1) voltage displayed on a scan tool will be over 1.0 volt (1000 mV). Try disconnecting the HO2S (Bank 1, Sensor 1), if the displayed voltage goes from over 1000 mV to around 450 mV, replace the HO2S (Bank 1, Sensor 1). |
Never solder the HO2S wires. For proper wire and connector repair, refer to Wiring Repairs in Engine Electrical.
Test Description
The number below refers to the step number on the diagnostic table.
-
This test determines if the conditions exist in order to set the DTC P0132.
-
If the HO2S (Bank 1, Sensor 1) is internally shorted, the HO2S (Bank 1, Sensor 1) voltage displayed on a scan tool will be over 1.0 volt (1000 mV).
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC Information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the scan tool data display indicate the HO2S (Bank 1, Sensor 1) voltage fixed above the specified value? | 1200 RPM 5.0L, 5.7L - 0.976 V (976 mV) 7.4L - 0.950 V (950 mV) | |||
Does the scan tool data display indicate the HO2S (Bank 1, Sensor 1) voltage near the specified value? | 0.40 V (400 mV) | |||
4 | The DTC is intermittent. Are any additional DTCs set? | -- | Go to the applicable DTC table | Go to Diagnostic Aids |
5 |
Was the HO2S (Bank 1, Sensor 1) Signal circuit shorted? | -- | ||
6 | Replace the Ho2S (Bank 1, Sensor 1). Refer to Heated Oxygen Sensor (HO2S) Replacement . Is the action complete? | -- | -- | |
7 | Replace the VCM. Important: When replacing the VCM, the new VCM will need to be programmed. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |
8 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
9 | Use the scan tool in order to display the Capture Info and the Review Capture Info functions. Are there any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
