Diagnostic article Generic OBD-II
P2AA5: EGR bypass overtemperature refers to the motor-driver stage
See why P2AA5’s H-bridge temperature evidence must be separated from coolant or exhaust temperature.
Read before applying this article
Documented application
2025 GM 25OBDG04A documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred.
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.
P2AA5 concerns excessive temperature reported by the H-bridge driving the EGR cooler-bypass motor. Although the component description discusses the bypass DC motor, the explicit measured criterion is driver temperature. A high exhaust or coolant reading is not a substitute for that electrical-driver evidence.
Identify the temperature that crossed its limit
The documented threshold is above 170°C at the H-bridge driver. The fault information is supplied through the hardware interface, and its status must not be indeterminate. An unavailable or uncertain hardware status should therefore not be treated as a confirmed normal driver temperature.
The monitor is enabled after cranking, with powertrain-relay supply above 11 V and an active diagnostic system. Clear-code or end-of-trip processing can affect that eligibility. Those states belong in the interpretation of an absent or incomplete test result.
Separate persistence from a replacement diagnosis
GM specifies 160 failed counts among 200 samples, with a 12.5 ms function task. The two-trip classification is separate from this sample-based temperature decision. A single displayed spike and a confirmed sequence provide different evidence.
Preserve the driver status, operating command and qualifying conditions. The source gives an example of internal actuator faults but does not establish a ranked cause or prove which component generated the heat. It also does not authorize bypassing protection or forcing the actuator to operate while overheated.
Source and applicability
2025 GM 25OBDG04A documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred. These criteria explain controller logic, not a complete repair procedure. 25OBDG04A, PDF page 1254.
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
EGR Cooler Bypass Control Circuit Driver Current/Temperature Too High Bank 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