Code Definition

P1142 — HO2S Bank 1 Sensor 2 Heater Circuit High Input

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

About P1142

P1142 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 P1142 is stored, the module has detected a signal or supply voltage higher than the expected operating range; 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.

P1142 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

The Powertrain Control Module (PCM) controls and monitors the heater element inside the Bank 1 Sensor 2 downstream oxygen sensor to warm it for post catalyst monitoring. DTC P1142 sets when the PCM detects a high voltage, or high input, on this heater monitor circuit, which typically indicates an open circuit, an open heater element, or loss of current flow so the monitored voltage stays high. On Mazda systems this most often points to an open in the downstream heater wiring, a corroded connector, or a burned out heater element. Driveability is usually normal, but the downstream sensor and cat...

Join TaT to view the complete code information and diagnostic details.

Quick Facts