Code Definition

P1144 — HO2S Bank 1 Sensor 3 Signal Above 0.45v (A/F Ratio Too Rich)

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

About P1144

P1144 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 P1144 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.

P1144 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

Some Mazda exhaust systems use a third oxygen sensor on Bank 1, Sensor 3, located furthest downstream after the rear catalytic converter, to refine fuel trim and confirm catalyst performance. DTC P1144 sets when this sensor signal stays above about 0.45V, telling the Powertrain Control Module (PCM) the exhaust at that point is rich or the sensor is biased high. This can reflect a genuine rich condition carried through from upstream fueling, sensor contamination, or a wiring fault holding the signal high. Driveability may be normal or include a fuel smell and poor economy, with the MIL illumina...

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