EN

Severity: Moderate Code type: Generic (all makes)

P2455 Code: Diesel Particulate Filter Pressure Sensor A Circuit High

The DPF pressure signal is stuck above its valid range – a wiring fault, or a filter that's badly restricted.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
Diesel Particulate Filter Pressure Sensor A Circuit High
System
Emission Controls · Powertrain
Safe to drive?
With caution
Typical repair cost
$50–$1,200
DIY difficulty
Moderate

P2455 sets when the DPF differential pressure signal climbs above the highest voltage a healthy sensor should produce, typically in the upper half-volt below the 5 V reference. Electrically, that happens when the sensor loses its ground, when the signal wire touches the 5 V reference or battery voltage, or when the sensor fails with its output stuck high. There is also a real-world path to this code that the low-side code doesn't have: a filter so packed with soot or ash, or a downstream sensing line so blocked, that the actual pressure difference goes beyond the sensor's measuring range. Telling these apart is the key to the repair, and it starts with what the reading does with the engine off.

Can I keep driving? Treat it seriously until you know which kind it is. If the reading is only high while driving, the filter may be severely restricted, and hard driving or towing can overheat the turbo and the DPF; get it checked before any long trip.

How to read P2455

How to read P2455P12243554
  1. P Powertrain
  2. 2 Generic (SAE)
  3. 4 Auxiliary emission controls
  4. 55 Specific fault

Symptoms

  • Check engine light, often with a DPF or exhaust filter warning
  • Reduced power, sometimes severe, especially under load
  • DPF pressure reading pinned at maximum on the scan tool
  • Frequent or failed regen attempts if the filter is truly loaded
  • Sluggish acceleration and higher exhaust temperatures when towing

Possible causes

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

  1. Open or high-resistance ground at the pressure sensor 26%
  2. Pressure sensor failed internally with its output stuck high 24%
  3. Signal wire shorted to the 5 V reference or to battery voltage 18%
  4. DPF severely overloaded with soot or ash, pushing the real pressure off the sensor's scale 16%
  5. Downstream sensing line blocked or pinched, inflating the measured difference 10%
  6. ECU input fault or incorrect replacement sensor 6%

Diagnosis step by step

Diagnostic flow: P24551Look at the reading with the engineoff2Voltage-drop test the ground3Check the signal wire for voltage4Assess the filter's real load5Inspect the downstream line6Repair and confirm

  1. Look at the reading with the engine off

    Key on, engine off: a DPF pressure value already at maximum means the problem is electrical or inside the sensor, because there's no exhaust flow. If it reads near zero at rest but climbs to the ceiling as soon as you rev the engine, suspect a real restriction or a blocked line.

    Tools: OBD-II scanner

  2. Voltage-drop test the ground

    With the sensor plugged in and the key on, measure between the sensor's ground pin and battery negative. More than about 0.1 V means a poor ground; clean or repair the ground path before going further.

    Tools: Multimeter

  3. Check the signal wire for voltage

    Unplug the sensor and measure the signal pin on the harness side with the key on. If you see about 5 V or battery voltage with the sensor disconnected, the signal wire is shorted to another circuit somewhere in the harness.

    Tools: Multimeter

  4. Assess the filter's real load

    If the wiring passes, compare measured and calculated soot load, check the ash value if available, and look at distance since the last completed regen. Very high values on both measured and calculated load mean the filter really is packed, which is the P2463 situation and needs attention quickly.

    Tools: OBD-II scanner

  5. Inspect the downstream line

    Follow the line from the sensor's low-pressure port to the port after the filter. A kinked hose, a tube crushed by a jack or a port full of soot keeps the low side from following the outlet pressure, which makes the difference read too high.

    Tools: Flashlight, Gloves

  6. Repair and confirm

    Fix the wiring or replace the sensor as the tests indicate, run any zero-point relearn, and clear the code. If the filter was truly overloaded, a scan-tool service regen within the manufacturer's limits or a professional cleaning comes next.

    Tools: OBD-II scanner

Where the parts are

Exhaust: catalytic converter and O2 sensors (Bank 1 / Bank 2) – P24551212345
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
Repair sensor ground or signal short No $100–$350
Replace DPF differential pressure sensor Yes $150–$400
Replace kinked or blocked downstream sensing line Yes $50–$200
Scan-tool service regeneration No $100–$300
Remove and professionally clean the DPF No $400–$1,200

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

Emissions / smog test impact

Depends

Diesel inspection rules vary by state and gross vehicle weight; where your truck is plugged in, P2455 with the check engine light on fails. If the root cause is a restricted filter, the only legal fix is cleaning or replacement, never removal.

Frequently asked questions

Sensor or filter – how do I know?

Check the reading with the engine off. A maxed-out value with no exhaust flowing is an electrical or sensor fault. A normal rest value that shoots to the limit under load points to a real restriction or a blocked line.

Is P2455 dangerous to drive with?

The electrical version mostly just causes reduced power. The restricted-filter version is more serious: high backpressure heats up the turbo and the filter, and a badly overloaded filter can crack during a regen.

Why did a new sensor not fix it?

Because the old one was probably reading correctly. If the ground is bad, the signal wire is shorted, or the filter really is packed, a new sensor reports the same high value.

Can I force a regen to clear it myself?

Only once you're sure the filter is intact and its load is within the manufacturer's limit for a service regen. Above that limit, a regen can overheat the filter, and the ECU on many trucks refuses it anyway.

Sources