P244A / P244B — DPF Differential Pressure Too Low / Too High
The pressure drop across the DPF is outside the expected window. Too high usually means blockage; too low often means a leak, a gutted filter, or a sensor/hose fault reading nonsense.
What commonly causes it
- ·Too high: genuine soot/ash blockage or collapsed substrate
- ·Too low: removed/hollowed filter (previous owner), major exhaust leak, split sensor hose
- ·Sensor drift after years of heat cycling
Test this before blaming the DPF
- ·Physically inspect the DPF can and welds — a previously gutted filter reads permanently low
- ·Verify the sensor zero-point with the engine off
- ·Smoke-test for exhaust leaks around the DPF flanges
Will cleaning fix it?
Only the 'too high from loading' case. A too-low reading needs the cause found first — cleaning an already-hollowed or leaking system fixes nothing, and we won't sell you a clean it doesn't need.
Engines this disproportionately affects
Check your vehicle & get a quote
Enter your registration — we'll identify the exact unit and give you the correct recommendation for this fault.
Vehicle data from the DVSA MOT history service. We confirm the exact unit on inspection. Privacy
Test evidence
Every unit is flow- and pressure-tested before and after cleaning. You get the readings, photo evidence and a completion certificate with the unit — proof for you and your customer, not marketing numbers.