This diagnostic applies only to vehicles built with Delphi heated oxygen sensors. To identify the heated oxygen sensor refer to
The powertrain control module (PCM) supplies a voltage of about 450 mV between the heated oxygen sensor (HO2S) high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when 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 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 above a predetermined voltage. If the PCM detects the voltage is above a predetermined voltage, a diagnostic trouble code (DTC) sets.
The HO2S voltage is more than 930 mV for 200 seconds.
Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
The numbers below refer to the step numbers on the diagnostic table.
If the voltage is above the specified value the condition is present.
Jumpering the HO2S low signal circuit to ground is necessary for the PCM to correctly measure the voltage on the HO2S high signal circuit. If the HO2S voltage is within the specified range, the PCM and HO2S high signal circuit are OK.
Step
Action
Values
Yes
No
Schematic Reference: Engine Controls Schematics
Important: This diagnostic applies only to vehicles built with Delphi heated oxygen sensors. To identify the heated oxygen sensor, refer to
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Important: With the engine running, observe the front HO2S voltage using a scan tool. If the front HO2S voltage is fixed below 200 mV, refer to DTC P0131 or P0151 .
Is the HO2S voltage more than the specified value?
930 mV
Go to Step 4
Go to Step 3
3
Does the DTC fail this ignition?
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 11
Go to Step 7
6
Go to Step 8
7
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.
Go to Step 9
8
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.
Go to Step 10
9
Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 .
Did you complete the replacement?
10
Replace the PCM. Refer to Powertrain Control Module Replacement .
11
Does the DTC run and pass?
Go to Step 12
12
With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?
Go to Diagnostic Trouble Code (DTC) List
System OK
This diagnostic applies only to vehicles built with Denso heated oxygen sensors. To identify the heated oxygen sensor refer to
Important: Never solder the HO2S wires. For proper wire and connector repair, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Check the following items:
An intermittent may be caused by any of the following conditions:
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Monitor the HO2S voltage of the opposite bank sensor. If the voltage activity of the opposite bank sensor is similar to the voltage activity of the suspect sensor, check for rich conditions that would affect both cylinder banks. An opposite bank sensor with normal HO2S voltage activity indicates the suspect HO2S is defective or a rich condition exists only on the suspect HO2S cylinder bank.
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 unapproved silicon RTV engine gasket material or the use of silicon based sprays or fluids within the engine. If the cause of this contamination is not corrected, the replacement HO2S will also get contaminated.
Important: This diagnostic applies only to vehicles built with Denso heated oxygen sensors. To identify the heated oxygen sensor, refer to
Is the HO2S voltage fixed more than the value specified?
Is the HO2S voltage within the value range specified?
351-551 mV
Is the voltage more than the specified value?
20 mV
Repair the short to voltage in the HO2S HIGH signal circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Important: Before replacing a contaminated HO2S, determine and repair the cause of the contamination.
Replace the HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 , or refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 .