Emission Control System - Diesel Particulate Filter (DPF) Differential Pressure
Indicates an issue with the DPF pressure sensor indicating a restriction.
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What it means (plain English)
The DPF differential pressure sensor measures the difference in pressure before and after the DPF. If the pressure before is much higher than after, the DPF is clogged and is restricting exhaust flow, which can lead to engine performance issues.
What the computer is actually seeing
The Engine Control Module (ECM) monitors the DPF pressure sensor. It expects the pressure difference to be within a specific range, typically around 0-5 inches of water column when normal. A significant drop or spike beyond this could trigger the code.
What a healthy reading looks like
Normal operation shows a differential pressure of 0-5 inH2O at idle and 5-15 inH2O during regeneration. Values higher than 15 inH2O may indicate a clogged DPF.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the DPF pressure sensor wiring and connectors for damage or corrosion. If found, repair or replace the damaged wiring/connectors and retest.
- 22. Check the DPF itself for visible signs of restriction or clogging. If the DPF is clogged, it may need cleaning or replacement.
- 33. Use a scan tool to check the DPF pressure sensor readings versus expected values. If the readings are abnormal, replace the pressure sensor and retest.
- 44. Conduct a forced regeneration using a scan tool if the DPF seems restricted. If the code returns immediately after this, the DPF may be faulty.
Common causes
- Clogged Diesel Particulate Filter
- Faulty DPF pressure sensor
- Exhaust leaks before or after the DPF
- Software/Calibration issues in the ECM
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally drivable but the engine performance may suffer. Address it soon to prevent further issues.
Will this code come back after clearing?
It may return if the underlying issue, like a clogged DPF, isn't resolved.
Why does this code often pair with other SPN codes?
Multiple emission system issues can occur simultaneously, especially in systems tied to exhaust flow and pressure.
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