What does code P1131 mean?

Q: What does code P1131 mean?

HO2S Bank 1 Sensor 1 Signal Below 0.45v AF Ratio Too Lean. P1131 on Mazda vehicles means the upstream heated oxygen sensor (HO2S) in Bank 1 is reporting a signal voltage below 0.45 volts while the powertrain control module (PCM) is commanding a stoichiometric air-fuel ratio. The PCM interprets this low voltage as a lean exhaust condition, meaning it sees more oxygen in the exhaust than expected and will try to add fuel to compensate.

DTC codes / Mazda codes / P1131

P1131 · MazdaHO2S Bank 1 Sensor 1 Signal Below 0.45v AF Ratio Too Lean

P1131 on Mazda vehicles means the upstream heated oxygen sensor (HO2S) in Bank 1 is reporting a signal voltage below 0.45 volts while the powertrain control module (PCM) is commanding a stoichiometric air-fuel ratio. The PCM interprets this low voltage as a lean exhaust condition, meaning it sees more oxygen in the exhaust than expected and will try to add fuel to compensate.

SystemPowertrain

Code typeMazda specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Guidance is general and written for Mazda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.