Diagnostic article Generic OBD-II
P045C: low-pressure EGR short-to-ground indication during drive
P045C is the low-pressure EGR command short-to-ground diagnosis in the cited strategy.
Read before applying this article
Documented application
2025 GM 25OBDG04B diagnostic parameter tables; the cited monitor only. Vehicle, engine and calibration applicability must be confirmed separately.
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.
P045C is the low-pressure EGR command short-to-ground diagnosis in the cited strategy. It uses excessive current through the H-bridge switches, reported by the hardware interface, rather than a standalone low-voltage comparison.
The measured criterion
Current above 8 A while the H-bridge driver is on is the published threshold. The same current magnitude appears in the opposite short-to-power category, so magnitude alone cannot establish the direction of the electrical fault. The hardware status and circuit context must remain attached to the reading.
The test runs after cranking with relay supply above 11 V, enabled diagnostics and determinate hardware feedback. It requires 240 failed counts among 300 samples on a 12.5 ms task, with Type A reporting.
What changes the next check
A driven-circuit overcurrent finding differs from an open-load result with the driver off. Establish which state produced the recorded fault before interpreting a resistance or current observation made under other conditions.
Verification should demonstrate normal hardware behavior during an eligible driven interval and use the proper electrical isolation procedure. This page does not distinguish a short in wiring from a fault within the actuator or electronics. It also does not provide a safe external-power test or authorize bypassing the driver's protection. The 8 A threshold applies to this documented implementation only.
Source and applicability
2025 GM 25OBDG04B diagnostic parameter tables; the cited monitor only. Vehicle, engine and calibration applicability must be confirmed separately. These tables describe detection logic, not a complete repair procedure or a component replacement verdict. gm-2025-04b, PDF page 1192.
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 B Control Circuit Low
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