OBD-II Diagnostic Trouble Code
P244B — Diesel Particulate Filter Differential Pressure Too High
The ECM measured a DPF differential pressure higher than expected for the current exhaust flow. This means the filter is heavily loaded with soot or ash, is restricted, or the sensor is reading high. The ECM sees this as excessive exhaust restriction across the DPF.
Severity 4/5
Truck-relevant
Stop within 50 mi
Severity
Stop within 50 mi
Diesel Particulate Filter Differential Pressure Too High
Code
P244B
Category
Powertrain
Subsystem
Aftertreatment
Truck-relevant
Yes
What this means for truckers
Stop within ~50 miles on a Cummins X15, Detroit DD15, PACCAR MX-13. Driving longer risks damaging adjacent components (turbo housing, head gasket, aftertreatment) and turning a $300 fix into a $3,000 fix.
Before you replace parts — try this first
P244B on the Aftertreatment system is most often excess soot load from short trips, excessive idling or interrupted regens — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Expect frequent or failed regens, reduced power, an engine derate, high exhaust back pressure and worse fuel economy. The DPF lamp may come on, and the truck may need a parked or forced regen. Severe cases drop to a heavy derate until serviced.
Common causes
- CommonExcess soot load from short trips, excessive idling or interrupted regens ($150–$400)
- CommonAsh-loaded DPF due for cleaning ($400–$900)
- OccasionalPlugged or frozen sensor tube, or a faulty differential pressure sensor ($100–$500)
- OccasionalEngine making excessive soot from leaking injectors, a restricted air intake, or an EGR or turbo problem ($500–$4000)
- RareFace-plugged DOC upstream causing restriction ($800–$2500)
How to fix
Check the sensor lines for blockage or ice and check sensor key-off zero
When to use: First step, especially in cold weather
Perform a parked or forced regen with a scan tool and recheck the differential pressure
When to use: When soot load is high and the sensor is good
Remove and clean or exchange the DPF and reset the ash and soot counters
When to use: When pressure stays high after a successful regen
Diagnose the source of excess soot, such as injectors, EGR, turbo boost or the air filter
When to use: When the DPF loads up again quickly after service
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P244A — Diesel Particulate Filter Differential Pressure Too Low
- → P244C — Exhaust Gas Temperature Too Low Bank 1
- → P244D — Exhaust Gas Temperature Too High Bank 1
- → P245A — EGR Cooler Bypass Control Circuit/Open
- → P246E — Particulate Filter Active/Intrusive Injection Quantity Too Low Bank 1
Frequently Asked Questions
Can I drive with code P244B?
Drive with caution. P244B is severity 4 — stop within ~50 miles. Most commercial diesel codes at this severity (turbo, fuel rail, transmission solenoid) can damage adjacent expensive components if left unrepaired. Get to a service location before highway-speed loads.
How much does it cost to fix P244B on a commercial truck?
Total repair cost ranges $100–$4000 depending on the root cause. The cheapest fix is usually the first one listed below — Excess soot load from short trips, excessive idling or interrupted regens — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P244B fail a DOT inspection?
Yes — P244B is an emissions-related code, and DOT inspectors check emissions compliance. An active emissions code with a check engine light can result in an out-of-service violation under FMCSA Part 393. The truck typically can't be moved until the code is cleared. Repeated emissions violations escalate to CSA scores.
What's the difference between P244B and related codes?
P244B is closely related to: P244A (Diesel Particulate Filter Differential Pressure Too Low), P244C (Exhaust Gas Temperature Too Low Bank 1), P244D (Exhaust Gas Temperature Too High Bank 1), P245A (EGR Cooler Bypass Control Circuit/Open). These codes share the same subsystem (aftertreatment) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P244B is set without the companions, the issue is more isolated.
How do I prevent P244B from coming back after a repair?
For P244B (Diesel Particulate Filter Differential Pressure Too High), prevention centers on the aftertreatment system. Run quality DEF (verify supplier — BlueDEF, PEAK, Yara Air1). Don't skip parked regens — when the dash asks for one, do it. Avoid extended idle time which fouls the DPF. Replace NOx sensors at the OEM interval (typically 400K miles).