Diagnostic article Generic OBD-II
P2231: heater influence is detected through upstream sensor current variation
The GM P2231 example checks bank-one upstream sensor current variation under qualified heater operation, rather than diagnosing a heater element from resistance alone.
Read before applying this article
Documented application
GM 2009 09OBDG04 Engine Diagnostics, cited bank-one upstream sensor/heater coupling monitor only. Document-level evidence does not establish per-code vehicle, engine or wiring applicability.
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.
P2231 concerns coupling between the bank-one upstream air/fuel sensor signal and its heater in this GM example. The table describes a wire-to-wire short diagnosis, but its monitored evidence is filtered pump-current variation. That is different from the separate heater open, short or heating-performance checks on the same page.
Heater operation qualifies the signal test
The printed current-variation boundary is greater than 0.00019 A, or 190 microamps, within the stated short sampling interval. The heater must be at operating temperature, with duty cycle between 20 and 80 percent. All injectors must be active, and the sensor interface diagnosis must be complete without its specified fault.
Other qualifications include battery voltage, engine speed and modeled exhaust temperature. Those conditions explain why a current fluctuation seen during warm-up or a different heater state is not automatically the same qualified fault event.
Separate coupling from simple heater failure
Record the exact sensor bank, heater command state and available signal information. A heater-circuit code may be relevant context, but it does not replace the evidence for signal-to-heater coupling. Likewise, an unexplained mixture correction is not by itself a verified short between those circuits.
The parameter table supplies no connector pinout or mandatory sensor replacement. The matching vehicle procedure must locate the coupling or other cause of the report. Exhaust heat and heater electrical controls require appropriate service precautions; these monitoring values are not instructions for probing an energized sensor circuit.
Source and applicability
GM 2009 09OBDG04 Engine Diagnostics, cited bank-one upstream sensor/heater coupling monitor only. Document-level evidence does not establish per-code vehicle, engine or wiring applicability.
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 Circuit Shorted to Heater Circuit Bank 1 Sensor 1
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