P244A: particulate-filter differential pressure is unexpectedly low

P244A sounds like a general low-pressure code, but this GM monitor is designed to detect a leaking or disconnected upstream pressure-sensing pipe. It compares measured particulate-filter differential pressure with a threshold derived from estimated soot loading and exhaust mass flow.

The threshold follows operating conditions

There is no single pressure limit in the row. A value that is plausible at one flow or soot estimate can be implausibly low at another. The counter is 240 failures out of 400 samples on a 12.5 ms task, with Type A, one-trip reporting.

The engine must be running and the pipe-temperature model must permit testing. Exhaust-flow and soot models must remain valid. Offset, electrical, quick-change and high-pressure diagnostic conditions also qualify the check. The continuation includes flow and exhaust-valve state requirements.

What the code establishes

Evaluate measured pressure alongside flow, modeled loading and the sensing-pipe arrangement. Low differential pressure alone does not establish a clean filter, because this monitor is looking for pressure information that is too low for the expected conditions. Nor does it prove that a particular pipe is disconnected.

Verify the qualified comparison after identifying the cause. An idle-only pressure reading or a cleared code cannot reproduce the map-based assessment. Exact enable limits and physical inspection procedures require the applicable service information.

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 822. GM diagnostic parameters, PDF page 823.