P2481: EGT sensor 5 circuit low across analog and digital systems

P2481 is headed as the EGT sensor 5 low-range electrical monitor. This table accommodates both an analog sensor and a digital thermocouple system. Knowing which architecture the vehicle uses is essential: the two branches assess different quantities and are not interchangeable meter specifications.

Two low-range comparisons

For the analog branch, the controller compares raw sensor resistance with a limit below 1 Ω. For the digital branch, it compares reported temperature with a limit below −72.80°C. A very low reported temperature can therefore be electrical diagnostic evidence rather than a believable exhaust temperature.

Both branches share a 19-failure requirement within 25 samples on a 100 ms function task. The row specifies Type B, two-trip behavior. The supply must be in range, ignition run/crank active, the engine not cranking, and initialization complete. A diagnostic reset or lost communication prevents the stated enabled condition.

Resolve the channel before testing

There is a real naming limitation: the heading and analog branch say sensor 5, while the digital comparison names EGT 4. The general description also mentions a maximum threshold despite this row's low comparisons. These are unresolved source details; they do not justify silently relabeling the installed probe.

Match the controller calibration, scan-tool channel and vehicle wiring documentation before applying either branch. On a digital system, distinguish communication with the module from the reported probe value. On an analog system, evaluate the relevant resistance circuit through the prescribed disconnected test procedure. This summary does not identify a failed part or authorize measuring resistance on a powered circuit.

Source and applicability

2025 GM 04A documented monitor only. Vehicle, engine and controller calibration applicability must be established separately; no model fitment is inferred from the file. GM PDF, physical page 1203.