P1131
Lack of HO2S Switch - Sensor Indicates Lean (Bank 1 Sensor 1)
What it means
This code means the oxygen sensor before the catalytic converter on Bank 1 is consistently reporting a lean air-fuel mixture, and the engine computer isn't seeing it switch back and forth as expected.
Is it safe to drive?
Driving with a persistent lean condition can lead to increased engine temperatures, potential engine damage, and catalytic converter damage over time. It's advisable to diagnose and repair this issue promptly.
Most likely causes
Vacuum Leaks
highLeaking vacuum hoses, intake manifold gaskets, or PCV system components can introduce unmetered air, causing a lean condition.
Faulty Front Oxygen Sensor (Bank 1 Sensor 1)
mediumThe oxygen sensor itself can become slow or faulty, inaccurately reporting a lean condition.
Low Fuel Pressure/Faulty Fuel Pump/Clogged Fuel Filter
mediumInsufficient fuel delivery can cause a true lean condition in the engine.
Dirty or Faulty Mass Air Flow (MAF) Sensor
mediumAn inaccurate MAF reading can cause the PCM to inject too little fuel, leading to a lean condition.
Related help
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