Diesel P244A: DPF Differential Pressure Too Low
P-Code P244A (FMI N/A) — Diesel Particulate Filter Differential Pressure Too Low
Quick Answer
P244A means DPF differential pressure is lower than expected, which can indicate exhaust bypassing the filter or a sensor/hose issue giving a falsely low reading.
Overview: Universal Diesel P-Code P244A
If the DPF was recently serviced, check the reinstall quality first - an improperly sealed connection is a common, easily overlooked cause.
Repair Snapshot
Time
1 - 3 Hours
Difficulty
Intermediate
Parts Cost
$50 - $2,500
Dealer Labor
$400+
Tools Required
- Scan Tool
- Visual Inspection Tools
What P-Code P244A Means
P244A means the pressure drop measured across the DPF is lower than expected, which can indicate a damaged or missing filter substrate allowing exhaust to bypass normal filtration, or a differential pressure sensor/hose issue giving a falsely low reading.
Symptoms Drivers Notice
- Check engine light
- Possible increase in visible exhaust smoke or soot
- No power loss typically associated with this fault alone
- May accompany other DPF efficiency codes
Most Likely Root Causes
Improperly sealed DPF housing after service
CommonAllows exhaust to bypass normal filtration, reducing the expected pressure drop.
Disconnected or misrouted diff pressure sensor hose
CommonGives a falsely low reading independent of actual filter condition.
Damaged or missing filter substrate
RarePhysical damage lets exhaust pass through with minimal restriction.
Common Misdiagnoses (Don't Waste Parts)
Assuming the sensor is faulty without checking hoses
Why it happens: It feels like the fastest explanation.
Do this instead: Check hose connection and routing before condemning the sensor.
Overlooking a recent service history
Why it happens: Techs may not have context on prior work.
Do this instead: Ask about any recent DPF removal or cleaning before diagnosing further.
Master Tech Commentary
Mechanic's Notes
Shop tip: if the DPF was recently serviced or removed for cleaning, always double-check that it was reinstalled correctly and sealed properly before assuming a sensor fault.
Step-by-Step Diagnostic Procedure
- Step 1: Inspect the DPF housing for damage or an improperly sealed connection that could let exhaust bypass the filter.
- Step 2: Check differential pressure sensor hoses for disconnection or improper routing.
- Step 3: Verify the sensor itself is functioning correctly using a scan tool comparison.
- Step 4: Inspect for any recent exhaust system service that might have left a connection loose.
- Step 5: Check for a missing or bypassed filter substrate if the housing has been serviced recently.
Live Data & Freeze-Frame Tips
Compare differential pressure readings against expected values during a regen cycle - values that stay abnormally low throughout point to a bypass or sensor issue.
Safety Warnings
- Allow the exhaust system to cool fully before inspection.
- Handle any removed filter carefully as it retains heat and soot residue.
When to Limp In vs Tow
Not required - the truck remains driveable.
Prevention Tips for Fleets & Owner-Operators
- Ensure proper reinstallation and sealing after any DPF service.
- Inspect sensor hoses at PM intervals.
- Address exhaust system service issues promptly.
Related Fault Codes
P2002
DPF efficiency below threshold, which can accompany a bypass condition.
Frequently Asked Questions
Does this mean the DPF is damaged?
Possibly, but check for a sensor/hose issue or improper reinstall first, since those are more common and cheaper to fix.
Can I drive with this code?
Yes, the truck remains driveable, though emissions performance may be affected.
Will this affect emissions testing?
Yes, if exhaust is genuinely bypassing the filter, it can affect emissions compliance.
How do I check for a sealing issue?
Inspect the DPF housing connections and clamps for proper torque and seating.
Is this an expensive repair?
It varies - a reseal or hose fix is inexpensive, while filter damage requires more significant repair.