Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step determines if the condition exists. If there is a short to ground condition with the HO2S circuits, the ECM commands open loop for the applicable sensor.
- 4: This step tests for a bias voltage across the reference voltage circuit and the low reference circuit of the HO2S. The bias voltage that you are measuring, is the voltage difference between the reference voltage circuit and the low reference circuit. If the reference voltage circuit or the low reference circuit of the HO2S is shorted to ground, the bias voltage will be above 1.5 volts, which indicates there is a condition with the circuits.
- 5: This step tests for a short to ground on the input pumping current circuit and the pump current circuit of the HO2S. The input pumping current circuit and the pump current circuit are connected internally within the ECM. If one of the circuits are shorted to ground, the other circuit will be affected. If you were to probe both circuits with a test lamp, the circuit that illuminates the test lamp brighter, is the circuit that is shorted to ground.
DTC P0131
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | - | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 |
IMPORTANT:
Inspect the heated oxygen sensor (HO2S) for being secure before proceeding with this DTC. A sensor that is loose could cause this DTC to set.
|
- | Go to Step 3 | Go to Step 4 |
| 3 |
|
- | Go to Step 4 | Go to Diagnostic Aids |
| 4 |
|
350-550 mV | Go to Step 5 | Go to Step 7 |
| 5 | Connect a test lamp between the input pump current circuit and battery positive voltage. Does the test lamp illuminate? |
- | Go to Step 6 | Go to Step 11 |
| 6 |
|
- | Go to Step 16 | Go to Step 13 |
| 7 | Measure the voltage between the reference voltage circuit of the HO2S and a good ground. Refer to Circuit Testing
in Wiring Systems. Is the voltage more than the specified value? |
1 V | Go to Step 8 | Go to Step 9 |
| 8 | Measure the voltage between the low reference circuit of the HO2S and a good ground. Is the voltage more than the specified value? |
1 V | Go to Step 12 | Go to Step 10 |
| 9 | Test the reference voltage circuit of the HO2S for a short to ground. Refer to Circuit Testing
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 13 |
| 10 | Test the low reference circuit of the HO2S for a short to ground or for an open. Refer to Circuit Testing
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 13 |
| 11 | Test for the following conditions:
Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 12 |
| 12 | Test for shorted terminals and poor connections at 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 16 | Go to Step 14 |
| 13 | Test for shorted terminals and poor connections at the ECM. 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 16 | Go to Step 15 |
| 14 | Replace the HO2S. Refer to Heated Oxygen Sensor 1 Replacement
. Did you complete the replacement? |
- | Go to Step 16 | - |
| 15 | Replace the ECM. Refer to Control Module References
in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? |
- | Go to Step 16 | - |
| 16 |
|
- | Go to Step 2 | Go to Step 17 |
| 17 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? |
- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |