Code Definition

P1874 — Oxygen sensor bank 1 sensor 3 crosscounts

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

About P1874

P1874 is a manufacturer-specific powertrain diagnostic trouble code recorded for GM vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1874 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.

P1874 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

This code relates to the Bank 1 Sensor 3 oxygen sensor, the rearmost sensor in the bank 1 exhaust stream, fitted downstream of the catalytic converter and used by the Engine Control Module to monitor catalyst efficiency rather than to control fuel directly. DTC P1874 sets when the ECM counts an insufficient number of voltage crosscounts, the transitions of the sensor signal between rich and lean, from this sensor over a calibrated period. Some vehicles use a third sensor in a bank where two catalysts are fitted in series, and this sensor sits after the rear catalyst. Very low crosscount activi...

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