The HO2S voltage remains within 150 mV of the bias voltage (about 450 mV) for a longer time than normal. The amount of time ranges between 42 seconds and 2 minutes.
If the condition is intermittent, refer to Intermittent Conditions .
The numbers below refer to the step numbers on the diagnostic table.
The HO2S should be allowed to cool before performing this test. If the HO2S heater is functioning, the signal voltage will gradually increase or decrease as the sensor element warms. If the heater is not functioning, the HO2S signal will remain near the 450 mV bias voltage.
This step ensures that the ignition 1 voltage circuit to the HO2S is not open or shorted. The test lamp should be connected to a good ground, in case the HO2S low signal or HO2S heater ground circuit is poor.
This step checks for an open or shorted HO2S heater element. The heater element resistance will vary according to HO2S temperature. A hot HO2S heater element will measure a much higher resistance than a HO2S heater element at room temperature. Allow the HO2S to cool before measuring HO2S heater element resistance.
|
Step |
Action |
Values |
Yes |
No |
|---|---|---|---|---|
|
Schematic Reference: Engine Controls Schematics |
||||
|
1 |
Did you perform the Diagnostic System Check-Engine Controls? |
-- |
Go to Step 2 |
|
|
If engine has just been operating, allow engine to cool for about one
half hour before proceeding.
Does HO2S voltage go from bias voltage to more than the first specified value or less than the second specified value? |
600 mV 300 mV |
Go to Intermittent Conditions |
Go to Step 3 |
|
|
3 |
Inspect the fuse for the HO2S 1 voltage circuit. Is the fuse open? |
-- |
Go to Step 13 |
Go to Step 4 |
|
Use a known good ground. Do not use the HO2S heater ground or low
signal circuit.
Does the test lamp illuminate? |
-- |
Go to Step 5 |
Go to Step 7 |
|
|
Connect the test lamp between the HO2S ignition 1 voltage circuit and the HO2S heater ground. Does test lamp illuminate? |
-- |
Go to Step 6 |
Go to Step 8 |
|
Does the resistance measure within the specified range? |
5-10 ohms |
Go to Step 9 |
Go to Step 12 |
|
|
7 |
Repair the open HO2S ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? |
-- |
Go to Step 14 |
-- |
|
8 |
Repair the open HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? |
-- |
Go to Step 14 |
-- |
|
9 |
Did you find and correct the condition? |
-- |
Go to Step 14 |
Go to Step 10 |
|
10 |
Test the HO2S high signal and HO2S low signal circuits for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? |
-- |
Go to Step 14 |
Go to Step 11 |
|
11 |
Inspect the HO2S high signal or HO2S low signal circuits for a poor connection at the PCM and HO2S. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring System. Did you find and correct the condition? |
-- |
Go to Step 14 |
Go to Step 12 |
|
12 |
Replace the HO2S. Refer to Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 2 , Heated Oxygen Sensor (HO2S) Replacement Bank 1 Sensor 1 , or Heated Oxygen Sensor (HO2S) Replacement Bank 2 Sensor 1 . Did you complete the replacement? |
-- |
Go to Step 14 |
-- |
|
13 |
Repair the short to ground in HO2S ignition 1 voltage circuit and replace the fuse. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? |
-- |
Go to Step 14 |
-- |
|
14 |
Does the DTC run and pass? |
-- |
Go to Step 15 |
Go to Step 2 |
|
15 |
With a scan tool, observe the Stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? |
-- |
System OK |
|