P244B: Diesel Particulate Filter Differential Pressure Too High (Bank 1)

P244B reports a pressure drop across the bank 1 particulate filter that is too large for the current exhaust flow. On GM's 3.0 L LZO the same monitor also catches a leaking or disconnected downstream pipe: depending on the sensor type it compares either the downstream pressure with a limit or the pressure-to-flow ratio, as a Type A code. A heavily loaded filter is the classic cause; on the 2020–2021 Cadillac XT4 with the 2.0 L diesel (LSQ), GM corrected an overstated soot reading that set P244B and reduced power with new ECM software. On 2025 L5P Silverado and Sierra HD, moisture that entered the sensor during washing can set it, so allow a night of drying before replacing parts. Hino calls P244B an incomplete regeneration and raised the torque cut to 70 % on 2013–2016 COE trucks. P2465 covers bank 2.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.

Symptoms

• MIL on, often with reduced power
• High soot level indication in the cluster
• Regeneration requested repeatedly

Most likely causes

• Filter heavily loaded with soot or ash
• Downstream pressure hose leaking or disconnected (GM LZO)
• Water in the differential pressure sensor after washing (GM L5P 2025)
• ECM calibration overstating soot load (Cadillac XT4 diesel, update)

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the soot load and differential pressure with a scanner
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
3. Check the differential pressure sensor's hoses
4. Check the temperatures before and after the filter
5. Fix any fuel injection or EGR codes before regenerating
6. Perform a regeneration while driving or at a repair shop when the diagnosis allows it

Good to know

• Repair difficulty: medium
• It can trigger limp mode.
• It affects emissions.

What each character of P244B means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• 4B: Specific fault in that system

Frequently asked questions

Can I keep driving with code P244B?

If the light is on steadily, take a highway drive or go to a repair shop soon. If the car is in limp mode or the light is flashing, do not push the engine.

What causes code P244B?

The most common causes are: filter heavily loaded with soot or ash; downstream pressure hose leaking or disconnected (GM LZO); water in the differential pressure sensor after washing (GM L5P 2025).

Related codes

• P244ADiesel Particulate Filter Differential Pressure Too Low (Bank 1)
• P2465Diesel Particulate Filter Differential Pressure Too High (Bank 2)
• P2452Diesel Particulate Filter Pressure Sensor A Circuit
• P2455Diesel Particulate Filter Pressure Sensor A Circuit High
• P2463Diesel Particulate Filter Restriction - Soot Accumulation (Bank 1)

Sources

• gsi.ext.gm.com: 25OBDG04B
• static.nhtsa.gov: MC 10197319 9999
• static.nhtsa.gov: MC 11011471 0001
• static.nhtsa.gov: MC 10115990 9999

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.