DPF Pressure Differential Low
Indicates low differential pressure across the DPF (Diesel Particulate Filter).
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer checks the pressure before and after the DPF to see if it's working properly; low pressure means the filter might be too clean or there's a sensor issue.
What the computer is actually seeing
The Engine Control Module (ECM) detects that the pressure differential between the inlet and outlet of the DPF is below the threshold, typically less than 1 psi.
What a healthy reading looks like
Pressure differential should be between approximately 0.5 to 3 psi when the engine is at operating temperature and under load.
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.
- 1Check the wiring and connector to the DPF pressure sensor for damage or corrosion.
- 2Test the voltage at the DPF pressure sensor; it should read around 0.5-4.5 volts depending on the pressure differential.
- 3Inspect the DPF for excessive cleaning or missing parts; a functioning DPF should have some back pressure during operation.
Common causes
- Faulty pressure sensor
- Wiring issues to the sensor
- DPF is too clean or has a fault
- ECM software glitch
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but you should address it soon to avoid potential exhaust issues.
Will this code come back after clearing?
It may return if the underlying issue isn't fixed, like a faulty sensor or wiring.
Why does this code sometimes pair with SPN 5401?
SPN 5401 indicates high pressure differential; both codes indicate issues with the DPF monitoring system.
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