Circuit Description
The powertrain control module (PCM) supplies a voltage of approximately 450 mV between the heated oxygen sensor (HO2S) high and low signal circuits. The heated oxygen (HO2S) sensor varies the voltage from approximately 1,000 mV if the exhaust is rich, to approximately 10 mV if the exhaust is lean.
The PCM monitors and stores the HO2S voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time during which the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period, and determines if the majority of the samples are out of the operating range.
The PCM monitors the HO2S voltage for being fixed below a predetermined voltage. If the PCM detects that the voltage is less than the predetermined voltage, a DTC sets.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0200, P0300, P0410, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1415, P1416, P1441, P1514, P1515, P1516, P1517, or P1518 are not set. |
| • | The ignition 1 signal is between 9-18 volts. |
| • | The loop status is Closed. |
| • | The secondary air injection (AIR) and the catalyst diagnostics are not active. |
| • | The throttle position (TP) indicated angle is between 3-70 percent more than the value observed at idle. |
| • | The Fuel Trim Learn is enabled. |
| • | The air fuel ratio is between 14.5-14.7 percent. |
| • | The fuel tank level remaining is more than 10 percent. |
Conditions for Setting the DTC
| • | The HO2S signal voltage remains below 200 mV. |
| • | The conditions exist for 31 seconds. |
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. |
Diagnostic Aids
Important:
• Before you service the PCM and throttle actuator control (TAC)
module, remove any debris from the module connector surfaces. When you diagnose
or replace the modules, inspect the module connector gaskets. Ensure
that the gaskets are correctly installed. The gaskets prevent contaminate
intrusion into the PCM/TAC modules. • Use the J 35616
connector test adapter kit for any test that requires
probing the PCM or probing a component harness connector. Using this
kit prevents damage to the harness and component terminals.
Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | The PCM sets this DTC when the vehicle runs out of fuel. |
| • | The sensor pigtail for the heated oxygen sensor (HO2S) wire may be contacting the exhaust manifold or contacting the exhaust system. |
| • | An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or for contamination. Refer to Wiring Repairs in Wiring Systems. |
| • | Inspect for an intermittent ground in the signal wire between the connector and the sensor. |
| • | Inspect for lean injectors. Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool . |
| • | Inspect for fuel contamination. Water near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust, and can set a DTC. Refer to Alcohol/Contaminants-in-Fuel Diagnosis . |
| • | Inspect the fuel pressure. The system will be lean if the fuel pressure is low. Refer to Fuel System Diagnosis . |
| • | Inspect for exhaust leaks. An exhaust leak near the HO2S can cause a lean condition. Refer to Exhaust System Description in Engine Exhaust. |
| • | Inspect for vacuum leaks or for crankcase leaks that can cause a lean condition. |
| • | Inspect the HO2S. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If the HO2S voltage is fixed well below 200 mV, this indicates a short to ground.
-
Using the Freeze Frame/Failure Records data may help to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data can help to determine how many miles have occurred since the DTC set. The Fail Counter and Pass Counter can also help to determine the number of ignition cycles since the diagnostic reported a pass or a fail. Operate the vehicle within the same Freeze Frame conditions that the PCM recorded, including the RPM, the vehicle load, the vehicle speed, and the temperature. This procedure isolates when the DTC failed.
-
A disconnected sensor should indicate a bias voltage. If the voltage is low, inspect the HO2S high signal circuit for a short to ground.
-
Disconnecting the PCM allows you to use a DMM in order to test the circuit continuity. This helps to locate an open circuit or a shorted circuit.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
2 |
Is the HO2S voltage less than the specified value? | 200 mV | Go to Step 4 | Go to Step 3 | ||||||||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||||
4 |
Is the HO2S voltage within the specified range? | 350-550 mV | Go to Step 5 | Go to Step 6 | ||||||||||||
5 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | ||||||||||||
6 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | ||||||||||||
7 | Test the HO2S high signal circuit for a short to the HO2S Low signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||||||||
8 | Inspect for poor connections at the harness connector of the HO2S. 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 12 | Go to Step 10 | ||||||||||||
9 | Inspect for poor connections at the harness connector of the PCM. 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 12 | Go to Step 11 | ||||||||||||
10 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 , or refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||||||
12 |
Does the DTC run and pass? | -- | Go to Step 13 | Go to Step 2 | ||||||||||||
13 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||||
