Air & Fuel Mixture ControlOBD2 Codes

P0131 – Meaning, Causes, Symptoms, & Fixes

Reading Time: 2 minutes


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.

What Are the Symptoms of Code P0131?

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

What Causes Code P0131?

  • 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

How Serious Is Code P0131? – 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 and Repair:

  • 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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  1. Cleared code and light did not come on again car is running fine

  2. The battery of the car was dead. I jump the car and as soon it turn on, the check engine light came on and this code appears. After a couple of hours, running around, erased the code, all back to normal. I tested the car days after and check light do not come back again. Your tool and service is awesome!!!

  3. I am so happy about this fixdaapp it amazing I recommend to any one thanks best regards Sam

  4. Could this code also be caused by driving to an higher elevation. Let’s say 2000-3000 feet above normal daily driving?

  5. FIXD diagnosed my check engine light correctly. Once I cleared the light I took the truck for a drive and did not notice any performance issues. Thanks for solving a potential problem. FIXD is the best purchase I ever made.

    1. My car all the sudden started putting and died, we got stranded with our 3month old baby and had to pat for a tow! I hope this dont cost me another arm and a leg! Fix showed 5 codes ?

  6. When I go to the shop I tell my mechanic what my car needs

  7. So my car is showing code 131 means my 02 sensor need changing …

  8. Could this code have anything to do with the fact I cut off the muffler

  9. My car all the sudden started putting and died, we got stranded with our 3month old baby and had to pay for a tow! I hope this dont cost me another arm and a leg! Fix showed 5 codes ?

  10. I changed both of my 02 sensor on my 02 Honda Civic and my engine light still stay on and am still getting the p0131 code what am I missing please help

    1. Did you disconnect the battery and reconnect it again after you changed your O2 sensors? If yes then you might need to replace your catalytic converter.

  11. My 2018 Buick Encore had a code of p301 which is misfire moved spark plug of number 1to 4 and the turned car back in to read a code now shows new code of p131 any idea why or how this could happen esp when goes from one code to another? Running very poor feels like going stall out. Any ideas?? Please help!!

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