Engine Aftertreatment System - Diesel Particulate Filter (DPF) Differential Pressure
Indicates a problem with the DPF differential pressure sensor.
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What it means (plain English)
The differential pressure sensor measures the difference in pressure before and after the DPF to determine if it's clogged or functioning properly. If this reading is off, it suggests a problem with the filter or the sensor itself.
What the computer is actually seeing
The ECM checks the voltage signal from the differential pressure sensor, expecting a certain range based on exhaust flow. A voltage far outside 0.5 to 4.5 volts indicates a fault.
What a healthy reading looks like
Expected voltage from the sensor is typically between 0.5V to 4.5V depending on pressure differences. Check for a specific vehicle service manual for precise values.
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. Start with a visual inspection of the wiring and connector on the differential pressure sensor for damage or corrosion. If damaged, repair or replace the wiring/connector.
- 22. Verify exhaust pressure readings using a scan tool. Start the vehicle and check the voltage from the differential pressure sensor. If outside 0.5V to 4.5V, proceed to step 3.
- 33. Check the condition of the DPF. If it's clogged and requires cleaning or replacement, address that issue. If the DPF appears clear, proceed to step 4.
- 44. Replace the differential pressure sensor if the readings are still out of range after checking wiring and DPF condition.
Common causes
- Clogged DPF
- Failed differential pressure sensor
- Wiring issues to the sensor
- Exhaust leaks affecting pressure readings
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; drivability may be affected, so drive cautiously and consider repairs soon.
Will this fault code come back after clearing it?
If the underlying issue isn't fixed, such as a clogged DPF or a faulty sensor, the code will likely return.
Why does this code sometimes pair with SPN 673?
SPN 673 indicates high DPF pressure, which can occur alongside SPN 676, showing that both the sensor and filter systems are interrelated.
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