EN

Severity: Moderate Code type: Generic (all makes)

P244A Code: DPF Differential Pressure Too Low Bank 1

The pressure drop across the DPF is lower than physically expected: a hose is off, or the filter is damaged.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
DPF Differential Pressure Too Low Bank 1
System
Emission Controls · Powertrain
Safe to drive?
Yes, short term
Typical repair cost
$40–$7,000
DIY difficulty
Moderate

A DPF always creates some resistance, so there must be a measurable pressure difference between its inlet and outlet that grows with exhaust flow. The differential pressure sensor reads that difference through two small tubes, and the ECM compares it with a value modeled from air mass and exhaust temperature. P244A sets when the measured difference stays well below the model even at high flow, while the sensor's electrical signal is still within range, which separates it from the circuit-low code. The most common reasons are mechanical and cheap: the inlet-side tube has slipped off, cracked or melted, or its port on the exhaust is plugged with soot or ice. If the plumbing checks out, the question becomes whether the filter itself still holds back exhaust: a cracked, melted or illegally hollowed-out DPF has almost no resistance.

Can I keep driving? Short-term driving is fine; with no usable pressure signal the ECM runs on its soot model and may regenerate more often or skip regens. Get it checked soon, because a damaged filter lets soot out and a missed overload can crack it further.

How to read P244A

How to read P244AP122434A4
  1. P Powertrain
  2. 2 Generic (SAE)
  3. 4 Auxiliary emission controls
  4. 4A Specific fault

Symptoms

  • Check engine light, sometimes with a DPF or exhaust filter warning
  • Differential pressure reading near zero even at high rpm
  • Black soot inside the tailpipe or visible smoke on acceleration
  • Regens running on a schedule instead of on actual load
  • Often no drivability change at all

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Inlet-side sensor tube disconnected, cracked, melted or leaking at a clamp 30%
  2. Differential pressure sensor with offset drift or a weak diaphragm 20%
  3. DPF cracked, melted or hollowed out so it barely restricts flow 18%
  4. Inlet-side port on the exhaust plugged with soot, rust scale or ice 14%
  5. Tubes swapped at the sensor after a repair, giving a negative or tiny reading 10%
  6. Exhaust leak between the turbo and the DPF inlet 8%

Diagnosis step by step

Diagnostic flow: P244A1Check for circuit codes first2Read pressure at rest, idle and highidle3Inspect the inlet tube end to end4Clear the exhaust-side port5Confirm tube orientation6Check the filter itself

  1. Check for circuit codes first

    If P2452–P2455 are stored, the sensor circuit itself has an electrical problem that must be fixed first. P244A alone means the signal is electrically valid but physically too low.

    Tools: OBD-II scanner

  2. Read pressure at rest, idle and high idle

    Key on, engine off it should read about zero. At idle a healthy filter shows a small positive value, and at a no-load high idle around 2,500–3,000 rpm it should roughly triple or more. A value that stays near zero or goes negative as rpm rises points to the tubes or a broken filter.

    Tools: OBD-II scanner

  3. Inspect the inlet tube end to end

    Trace the tube from the sensor port marked for the upstream side to the fitting ahead of the DPF. Look for a slipped hose, pinholes, soft or burned sections and loose clamps; a smoke tester applied to the tube quickly reveals leaks.

    Tools: Flashlight, Smoke machine

  4. Clear the exhaust-side port

    Remove the tube at the exhaust and blow through the metal pipe and port with low-pressure shop air. A plugged port on the inlet side lets the sensor see almost no pressure.

    Tools: Pliers

  5. Confirm tube orientation

    Compare the tube routing with the sensor markings or a service diagram. Swapped tubes are a common mistake after DPF work and make the reading negative when rpm rises.

    Tools: Flashlight

  6. Check the filter itself

    If sensor and tubes are good, wipe the tailpipe clean and drive; fresh soot means the filter is passing particles. A borescope through the sensor port or removing the DPF shows cracks, melted areas or an empty housing.

    Tools: Flashlight, Gloves

Where the parts are

Exhaust: catalytic converter and O2 sensors (Bank 1 / Bank 2) – P244A1212345
Exhaust: catalytic converter and O2 sensors (Bank 1 / Bank 2)
  1. 1Upstream O2 sensor
  2. 2Catalytic converter
  3. 3Downstream O2 sensor
  4. 4Diesel particulate filter
  5. 5Turbocharger

Repair options & costs

RepairDIY?Estimated cost
Reconnect or replace sensor tubes and clamps Yes $40–$200
Replace DPF differential pressure sensor Yes $150–$400
Clear or replace plugged exhaust-side pressure pipe Yes $60–$250
Repair exhaust leak ahead of the DPF No $150–$500
Replace cracked or removed DPF No $2,500–$7,000

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Emissions / smog test impact

Depends

In states that OBD-test diesels, P244A with the check engine light on fails; where a visual check is part of the test, a missing DPF fails too. A hollowed-out filter is illegal federal tampering regardless of your state's testing rules.

Frequently asked questions

How is P244A different from P2454?

P2454 is an electrical fault: the sensor signal voltage is below its valid range. P244A means the signal is electrically fine but the pressure it reports is too low to be real for the exhaust flow.

I bought a used diesel with P244A. Should I worry?

Check whether the DPF is intact. A filter that has been emptied out produces exactly this code, is illegal, and puts the cost of a new filter on you.

Can a melted hose really cause this?

Yes, and it's one of the most common causes. The inlet tube runs close to hot exhaust parts; once it leaks, the sensor sees only a fraction of the real pressure.

Sources