Code Definition

P1137 — HO2S Bank 1 Sensor 2 Not Switching (Fuel Control Limit Reached)

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Mazda

About P1137

P1137 is a manufacturer-specific powertrain diagnostic trouble code recorded for Mazda vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1137 is stored, the module has detected a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1137 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

On this Mazda system the Bank 1 Sensor 2 downstream oxygen sensor, located after the catalytic converter, contributes to longer term fuel control trimming and catalyst monitoring. DTC P1137 sets when this sensor stops switching and the rear fuel control correction reaches its limit, meaning the PCM can no longer bring the downstream reading to target, pointing to a lazy or failed downstream sensor or a real mixture or exhaust condition. Because the downstream sensor sees post catalyst gas, a stuck or biased signal also affects the catalyst efficiency monitor. The driver may notice little chang...

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