P04D1: EGR temperature raw resistance above the high boundary

P04D1 checks the upstream low-pressure EGR temperature signal for excessive raw resistance. The listed failure boundary is greater than 631,646.13 ohms in this specific calibration.

Do not confuse high resistance with hot exhaust

The monitor is an electrical-range check. Its high label qualifies the raw resistance, so it does not independently prove that EGR temperature is too high. The physical temperature interpretation depends on the actual sensor characteristic, which this summary does not supply.

The check runs outside cranking with relay voltage above 11 V and the calibration enabled. It counts 30 failures among 38 samples on a 100 ms task and lists Type A, one-trip reporting.

What changes verification

Unlike a post-soak rationality comparison, this row does not require agreement with fuel and intake-air temperatures. A normal comparison at one cold start therefore cannot by itself rule out an intermittent high-resistance event later under eligible electrical monitoring.

Preserve the raw signal and fault timing, then verify that the appropriate monitored interval completes without the high-range condition. The number is a monitor threshold, not a replacement-part specification or an instruction to measure resistance while the circuit is powered. The table does not isolate the sensor from its connections or controller input. That separation requires the vehicle-specific circuit procedure and correct sensor identification.

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 1212.