Diagnostic article Generic OBD-II
P2085: rapid raw-temperature changes from EGT sensor 2
P2085 monitors exhaust-temperature sensor 2 for repeated abrupt changes while its electrical and communication checks remain valid.
Read before applying this article
Documented application
Documented 2025 GM diagnostic parameter monitor in 25OBDG04B.pdf; model, engine and calibration applicability require vehicle-specific confirmation.
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.
P2085 is labeled exhaust-temperature sensor 2 circuit intermittent. GM's reviewed strategy gives that label a specific meaning: the raw temperature signal changes too quickly for the expected sensor behavior. This is separate from an out-of-range high/low result or a lost-communication event.
What qualifies as excessive change
The table uses an absolute raw-temperature difference above 100°C, accumulated as 12 failures within 25 samples. The task runs every 100 milliseconds. These are change-and-persistence criteria, not an absolute exhaust overtemperature limit.
The enable window places unfiltered temperature at least at 140°C, with the continuation giving the upper 1,070°C boundary. Relevant sensor electrical faults and communication loss must be absent. Sensor initialization must also be complete, with cranking excluded and valid Run/Crank and supply conditions.
Interpreting the fault record
The source lists sensor internal malfunction, wiring deterioration and connector electrical issues as failure modes the quick-change test can detect. It does not identify which has occurred, and a smoothed scan display may hide the raw discontinuity being assessed.
Verification should therefore focus on the sensor 2 raw signal and monitor completion within its enabled temperature range. A stable reading immediately after a cold start may not exercise the check. The listed reporting is Type B over two trips. This summary supports no generic probe-replacement decision or location assumption; exact sensor mapping and electrical isolation must be established from the applicable vehicle service information.
Source: GM monitor, PDF page 1397; GM monitor, PDF page 1398.
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
Exhaust Gas Temperature Sensor Circuit Intermittent Bank 1 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