Diagnostic article Generic OBD-II
P2273: Interpreting a rear-sensor rich-bias check when the table wording conflicts
Read P2273’s lean-response failure criterion with the original source’s contradictory strategy text kept explicit.
Read before applying this article
Documented application
2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P2273 is the bank 2 sensor 2 biased/stuck-rich code. The GM row's malfunction column evaluates the minimum rear-sensor voltage during a commanded lean shift. Its strategy text, however, describes a maximum voltage during a rich command. Both wordings appear in the original PDF, so they are not silently treated as equivalent.
The failure column describes inadequate lean response
The printed criterion is a minimum bank 2 secondary-sensor voltage remaining above approximately 0.2002 V while shifting lean. The continuation describes an intrusive state sequence and qualifications for exhaust flow, sensor readiness and catalyst temperature.
This is different from declaring any high rear-sensor voltage during normal operation a failure. The command and the opportunity for the exhaust response to arrive are part of the diagnostic evidence.
Resolve the detailed procedure before applying thresholds
The continuation also contains mixed bank references in parts of the state sequence. This article therefore explains the supported lean-response criterion without presenting the entire sequence as a verified universal workshop test.
Useful observations include commanded mixture, upstream confirmation, rear-sensor minimum response and monitor eligibility. They help distinguish a response failure from an observation made before the proper test conditions existed. The code does not independently isolate the sensor, mixture cause or catalyst. Exact calibration information is needed to resolve the wording and apply the correct procedure before a component is selected.
Source and scope
2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join. These are documented monitor criteria, not a universal repair procedure. GM PDF, physical page 497 · GM PDF, physical page 498 · GM PDF, physical page 499 · GM PDF, physical page 500 · GM PDF, physical page 501.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 2
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT