P24A4: DPF loading reaches the severe restriction threshold

The generic P24A4 description says soot accumulation too high. The cited GM entry instead labels the condition DPF restriction due to ash accumulation and describes a replacement-level clogged filter. That difference in wording must remain visible; a code lookup alone cannot establish actual ash mass or a final replacement decision.

The documented model threshold

The controller uses a pressure-derived soot model with a configurable correction block. Its threshold is above 300% during soot loading or above 320% in other filter states. The counter is 20 failures out of 30 samples on a 100 ms task, with Type A, one-trip reporting. These are calibrated model percentages, not a direct physical fill measurement.

Pressure-sensor rationality, temperature data, airflow, atmospheric pressure and exhaust-flow validity all qualify the result. The continuation also requires low icing risk for sensing pipes and a valid pressure-based model.

What changes the next decision

Separate this severe-loading entry from the lower-threshold service-regeneration monitor P2463. Do not assume that a regeneration suitable for the latter is authorized for P24A4. First validate the information supporting the restriction estimate, then follow the exact professional service procedure for filter assessment. Confirmation requires a credible model and completed monitor after the prescribed remedy; clearing codes does not establish that severe restriction has been resolved.

Source and application limits

This explanation covers the cited 2025 GM monitor. Confirm the vehicle and calibration in its service information before applying these limits; inclusion in this file does not establish model compatibility. GM diagnostic parameters, PDF page 1489. GM diagnostic parameters, PDF page 1490.