Diagnostic article Generic OBD-II
P2428: exhaust protection checks both temperatures and temperature differences
GM P2428 can result from an excessive individual exhaust temperature or an excessive difference between monitored locations, so one reading is incomplete evidence.
Read before applying this article
Documented application
GM 2015 15OBDG04 Engine Diagnostics, cited exhaust-temperature protection 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.
P2428 is an excessive-exhaust-temperature diagnostic intended to protect the particulate filter in this GM calibration. The table defines several alternative failure paths. It is therefore not a single universal threshold applied to one unspecified exhaust sensor.
The controller checks individual and relative values
The source includes separate high-temperature limits for the oxidation-catalyst upstream, oxidation-catalyst downstream and particulate-filter downstream measurements. It also evaluates the difference across the oxidation catalyst and the difference between the later monitored locations.
The listed failure must persist for six seconds, with evaluation at a 0.1-second rate when the general enabling and inhibition conditions are satisfied. A technician must identify which alternative condition was actually present; a lone temperature reading can miss an excessive difference between otherwise plausible reports.
Establish whether the thermal evidence is trustworthy
Preserve all relevant temperature traces and operating-state information. A reported overtemperature can require checking measurement validity as well as the physical exhaust process. The code alone does not prove that the particulate filter is blocked or that a particular sensor must be replaced.
The parameter table is not an instruction to initiate regeneration or to keep operating until a fault returns. Those decisions require the applicable vehicle procedure and the actual thermal condition. Exhaust components can present serious heat hazards, so professional diagnosis and repair verification must use the correct service controls rather than treating the printed calibration limits as safe handling temperatures.
Source and applicability
GM 2015 15OBDG04 Engine Diagnostics, cited exhaust-temperature protection monitor only. Document-level evidence does not establish per-code vehicle, engine or wiring applicability.
General Motors source, physical page 235 · General Motors source, physical page 236
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 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