DPF Differential Pressure Too Low
The HINO-P244A (Hino) diesel fault code means: DPF Differential Pressure Too Low. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $500-$3,500
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Common Symptoms
- DPF / Regen lamp illuminated
- Progressive derate (5 mph in final stage)
- Frequent request for manual regen
- Reduced power and fuel economy
- Elevated EGTs during regen
Probable Causes (Ranked by Likelihood)
- Short-haul urban delivery duty cycle preventing successful regens (Hino 195 box truck especially) Very Likely
- DPF ash load exceeding service threshold (Hino DPF cleaning interval 200K-300K mi) Likely
- Upstream fault (EGR, injector, rail pressure) preventing proper regen temperature Likely
- Failed EGT or differential pressure sensor Possible
- Plugged delta-P sample tubes giving invalid readings Possible
Step-by-Step Diagnostic Procedure
Confirm P244A on Hino DX3. Capture soot %, ash %, and distance/time since last successful regen.
Attempt manual / parked regen — outlet EGT should exceed 1000°F for 20+ minutes. Failure to climb indicates upstream DOC / HC doser issue.
Remove and clean delta-P sample lines — soot plugs are a recurring cause of bogus P244A/B codes on Hino.
If ash load is over limit, send DPF for bake-and-blow service or replace; ash cannot be regenerated away.
After repair, reset soot counters with DX3 and drive a representative duty cycle to verify regen completes.
Frequently Asked Questions
What does Hino code P244A mean?
Hino diagnostic trouble code P244A (DPF Differential Pressure Too Low) is a moderate-severity fault on Hino medium-duty diesel engines. It indicates a problem in the DPF / aftertreatment that should be verified with a scan tool (Hino DX3 / DX4) before replacing any parts.
Can I drive my Hino truck with P244A?
Short runs may be possible but do not ignore — Hino medium-duty aftertreatment faults cascade quickly into 5-mph derate or no-restart. Schedule diagnosis immediately.
How much does it cost to fix Hino P244A?
Typical repair cost runs $500-$3,500. Sensor, wiring, and DEF-related repairs fall at the low end; DPF service, turbo, injector, and EGR cooler work fall at the high end and may require dealer-level programming.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P244A on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: