P244B code meaning
Diesel Particulate Filter Differential Pressure Too High (Bank 1)
Powertrain system Generic code P24xx codes Check engine light
What P244B means
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.
P244B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.3 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P244B
- MIL on, often with reduced power
- High soot level indication in the cluster
- Regeneration requested repeatedly
Common causes of P244B
- Most likelyFilter heavily loaded with soot or ash
- PossibleDownstream pressure hose leaking or disconnected (GM LZO)
- PossibleWater in the differential pressure sensor after washing (GM L5P 2025)
- Less likelyECM calibration overstating soot load (Cadillac XT4 diesel, update)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
DPF diff pressure sensor
What each part of P244B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 4B | The exact fault in that area. |
What to do next
- Note P244B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P244B
What does P244B mean?
P244B means "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. It is a generic code, so it means the same on every make.
Is it safe to drive with P244B?
Drive gently and only to a workshop. With P244B the car can go into limp mode (reduced power) to protect itself.
Will P244B fail an emissions test?
Yes, it can. P244B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P244B to fix?
Difficulty: medium. A typical repair takes 0.3 to 4 hours of work. This is a job for a workshop.
Will P244B clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.