Diagnostic article Generic OBD-II
P2ADC: A high temperature report from the smart reductant tank sensor
P2ADC comes from the smart reductant tank temperature sensor’s own range calculation and is transmitted to the controller.
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Documented application
2025 GM 04B documented monitor only; module and calibration applicability must be matched to the vehicle.
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.
P2ADC identifies an excessively high temperature report from the reductant tank's UTLC smart sensor in the cited DEFC strategy. The smart sensor performs the range computation and sends an error flag over SENT. The controller is not simply applying an unexplained high-voltage limit to a conventional analogue temperature input.
What the documented monitor requires
The threshold is a reductant UTLC temperature measurement above 90°C. The row lists two seconds of evaluation with a four-sample, 0.5-second time base. Vehicle power mode must be active, which the document defines to include accessory, run, start request or propulsion modes.
SENT communication faults and internal controller faults inhibit the check. This matters when a high-temperature code appears with communication trouble: establish whether the received sensor information was considered valid before interpreting a displayed temperature as reliable physical evidence.
Avoid a misleading circuit assumption
The dictionary says circuit high, but the source's failure criterion is reported temperature and an internally generated sensor flag. Neither that wording nor the 90°C threshold identifies a connector pin voltage or establishes that the tank contents truly reached that temperature.
Useful follow-up evidence includes the UTLC temperature, sensor error status and communication health during an active power mode. A one-time plausible temperature after clearing does not verify completion of the sampling decision. The summary provides no connector test or replacement instruction; match the smart-sensor diagnostic procedure to the vehicle before making either conclusion.
Source and applicability
2025 GM 04B documented monitor only; module and calibration applicability must be matched to the vehicle. GM PDF, page 208.
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
Reductant Tank Temperature Sensor B Circuit High
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