DTC P0131: Primary HO2S (Sensor 1) Circuit Low Voltage
- Reset the ECM/PCM (see page 11-312).
- Start the engine. Hold the engine at 3,000 rpm (min-1) with no load (in Park or neutral) until the radiator fan comes on.
- Check the primary HO2S (Sensor 1) output voltage with the scan tool during acceleration using wide open throttle.
Does the voltage stay at 0.5 V or less?
YES |
- Go to step 4. |
NO |
- Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the primary HO2S (Sensor 1) and at the ECM/PCM. |
- Check the fuel pressure (see page 11-431).
Is it normal?
YES |
- Go to step 5. |
NO |
- Repair the fuel supply system. |
- Turn the ignition switch OFF.
- Disconnect the primary HO2S (Sensor 1) 4P connector.
- Turn the ignition switch ON (II).
- Check the primary HO2S (Sensor 1) output voltage with the scan tool.
Does it stay at 0.5 V or less?
YES |
- Go to step 9. |
NO |
- Replace the primary HO2S (Sensor 1). |
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- Turn the ignition switch OFF.
- Disconnect ECM/PCM connector A (31P).
- Check for continuity between the primary HO2S (Sensor 1) 4P connector terminal No. 2 and body ground.
PRIMARY HO2S (SENSOR 1) 4P CONNECTOR
Terminal side of male terminals
Is there continuity?
YES |
- Repair short in the wire between the ECM/PCM (A6) and the primary HO2S (Sensor 1). |
NO |
- Substitute a known-good ECM/PCM and recheck (see page 11-313). If symptom/indication goes away, replace the original ECM/PCM. |
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