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Detroit Diesel SPN 3250 FMI 16 indicates that the pressure difference across the Diesel Particulate Filter has exceeded the acceptable operating threshold. This code appears on DD13, DD15, and DD16 engines and signals that exhaust flow through the DPF is being restricted, which directly impacts engine performance and will trigger derate conditions if not addressed promptly.
Symptoms
- Check engine light on
- DPF warning light illuminated
- Reduced engine power
- Engine derate condition possible Increased exhaust back pressure
- Regeneration cycles may be more frequent
- Black smoke from exhaust possible
Cause
This code triggers when the differential pressure sensor detects a pressure drop across the DPF exceeding the maximum threshold. Common causes include:
- Heavily soot loaded DPF restricting exhaust flow
- High ash accumulation inside the DPF
- Failed or incomplete regeneration cycles
- Clogged or damaged DPF substrate
- Faulty differential pressure sensor or blocked sensor lines
- Engine burning excessive oil accelerating ash buildup
- Collapsed or damaged DPF internal structure
Can You Keep Driving?
Limited driving may be possible but high differential pressure indicates severely restricted exhaust flow which reduces engine performance and can cause damage. A regeneration should be attempted immediately. If pressure remains high after a successful regen the DPF likely needs professional cleaning or replacement.
Recommended Action
Attempt a parked regeneration to reduce soot load and pressure. If the differential pressure remains high after a successful regen, inspect the sensor lines for blockages before condemning the DPF. If lines are clear the DPF should be removed for professional cleaning or inspection. Also check for excessive oil consumption that may be contributing to rapid ash accumulation.
It means the pressure difference across the DPF has exceeded the maximum acceptable threshold, indicating the filter is restricting exhaust flow due to soot, ash, or physical damage.
The most common causes are a heavily soot or ash loaded DPF, failed regeneration cycles, a clogged or damaged filter substrate, or a faulty differential pressure sensor.
Short distances may be possible but high back pressure from a restricted DPF will reduce engine performance and can cause damage if ignored. Attempt a parked regen as soon as safely possible.
Yes. Excessive differential pressure across the DPF will cause the ECM to trigger derate conditions to protect the engine from damage caused by high exhaust back pressure.
Perform a parked regeneration to reduce soot load. If pressure remains elevated after regen check the sensor lines for blockages then have the DPF professionally cleaned or replaced if needed.
Related codes
Need Immediate Help With This Fault Code?
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Important Notice
The information provided above is for general informational purposes only and should not replace official OEM service procedures. Always consult the manufacturer’s service manual or a qualified diesel technician before performing repairs. Operating a vehicle with active fault codes may result in further damage.