What is code spn 3251?

What is code spn 3251?

SPN 3251/FMI 0 – EPA07 This diagnostic is typically Diesel Particulate Filter (DPF) Pressure Out of Range Very High. This fault code sets when the DPF outlet pressure is greater than 35 kPa (5 psi) for more than 10 seconds.

What should DOC inlet pressure be?

The DOC inlet pressure should be less than 9 kPa (1.3 psi) for a 1-Box ATS and 12 kPa (1.74 psi) for a Two-Box ATS.

How do DPF pressure sensors work?

How does a DPF pressure sensor work? The DPF sensor measures the pressure drop across a DPF. A DPF pressure drop increases with increase in the soot mass accumulated in the DPF. Small soot mass accumulation results in lower DPF pressure drop, while high soot mass accumulation would yield higher DPF pressure.

What does Engine 0 mean on a Freightliner?

Eng 0 code means that there is a fault, but it does not point to what it is. To know why the Eng 0 code got illuminated, go to the diagnostic section.

What causes DOC face plugging?

Under normal operation, a DOC would not be expected to plug. However, poorly maintained engines or operation in extreme cold may cause face plugging. The two most common engine failures that can plug a DOC are fuel injector or turbocharger failures that result in fuel or lube oil being fed into the exhaust system.

What is a doc sensor?

An exemplary exhaust treatment device includes a diesel oxidation catalyst (DOC). Inlet and outlet temperature sensors are typically associated with the DOC to monitor exhaust temperatures. Proper functioning of the temperature sensors is required to enable the vehicle control system to monitor exhaust temperature.

How do you test a DPF pressure sensor with a multimeter?

If everything passes physical inspection, you can test the DPF differential pressure sensor using a multimeter set to 20V and a pressure gauge. With the battery on and engine off, connect the multimeter ground to the negative battery terminal and run a quick plausibility by checking the voltage of the battery.