P2456
Particulate Filter Pressure Sensor A Circuit Intermittent/Erratic
Auxiliary emissions control (diesel)
Generic OBD-II
Medium
What it means
P2456 means the diesel particulate filter's "A" pressure sensor is sending an unstable or dropping-out signal to the engine computer. The ECM uses this reading to judge how clogged the filter is and when to run a regeneration, so an erratic signal is usually a wiring, connector, or sensor fault rather than an engine problem.
Medium
Can I keep driving? Usually drivable, but the ECM can't reliably monitor the particulate filter, so it may trigger a regen fault or reduced-power mode over time.
Common symptoms
What you'll notice
- Check-engine light on
- Signal that drops out or reads erratically to the ECM
- Possible failed or incomplete DPF regeneration
- Occasional reduced-power / limp mode if the fault repeats
Common causes
Most likely first
- Loose, corroded, or backed-out connector at the particulate filter pressure sensorLikely
- Chafed, pinched, or intermittently shorting wiring in the sensor circuitCommon
- Failing particulate filter differential-pressure sensorCommon
- Blocked, cracked, or moisture-filled pressure hoses to the sensorLess often
- Poor ground or intermittent ECM connectionLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data, then wiggle-test the sensor connector and harness to reproduce the dropout.
- Inspect the connector and pins for corrosion, spread terminals, or moisture; clean and reseat.
- Check the pressure hoses to the sensor for cracks, soot blockage, or trapped condensation.
- Measure the sensor's reference voltage, ground, and signal against spec; back-probe while wiggling the harness.
- If wiring and connections are good, replace the differential-pressure sensor, then clear and road-test.
FAQ
Quick answers
Is it safe to drive with P2456?+
Short term usually yes, but because the ECM can't trust the filter pressure reading it may block regeneration or drop into reduced power, so get it checked soon.
Can I just clear P2456?+
It clears, but an intermittent wiring or connector fault will set it again. Find and fix the loose connection or failing sensor first.
Related codes
Often seen with P2456
Read & clear P2456 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX