P0131 – Meaning, Causes, Symptoms, & Fixes

Code P0131 Definition

O2 Sensor Signal Low Voltage (Bank 1, Sensor 1)

What Does P0131 Mean?

Code P0131 is a result of the oxygen A/F sensor incorrectly detecting the air to fuel ratio of the exhaust. This ratio is sent to the ECM which uses this data, along with comparisons to the outside air, to regulate the air to fuel ratio needed by the engine. This DTC code is the result of this ECM detecting either a voltage outside of the specified range, or an improper air to fuel ratio.

P0131 Symptoms

  • Check engine light
  • Heavy smoke from exhaust
  • Vehicle running rough
  • Lower fuel economy

P0131 Cause

  • Frayed oxygen sensor circuit wiring/connectors
  • Malfunctioning oxygen sensor bank 1
  • Faulty O2 sensor heater circuit
  • Vacuum leaks
  • Fuel pressure too high/low
  • Malfunctioning ECM

Code P0131 Severity – Severe 

This trouble code indicates a major problem which could range from your vehicle running poorly, to it failing to run at all. It is recommended if you see this code to seek maintenance immediately.

Code P0131 Common Diagnosis Mistakes

Prematurely replacing the oxygen (O2) sensor before verifying that the engine code is actually in the oxygen sensor circuit. This can be accomplished by simply clearing the code and performing a test drive.

P0131 Diagnosis

  • Tools Needed to Diagnose:

Difficulty of Diagnosis and Repair – (1-5)

  1. Check to see if there are any other codes along with P0131 and clear your Check Engine Light with FIXD.
  2. Check the freeze frame data for the O2 sensor to pinpoint the issue.
  3. Conduct a visual inspection of bank 1 sensor 1wiring around the oxygen sensor for fraying or disconnection.
  4. Consider using a voltmeter to check the voltage of bank 1 sensor 1 to confirm it is operating in the specified range
  5. Consider replacing oxygen sensor if the check-engine light persists.
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