Diesel Engines Engine
Diagnostics
• Since the filter itself creates a certain resistance in the exhaust gas flow, the signal of the
DPF differential pressure sensor is also used to determine the filter condition.
M6FL_01062
X Exhaust-gas volume flow Y Differential pressure
1 Blocked condition of filter 5 Regenerated condition of filter
2 Overloaded condition of filter 6 Damaged condition of filter
3 Loaded condition of filter 7 Differential pressure limit
4 Intermediate condition of filter
• If the value measured by the DPF differential pressure sensor is above a certain limit, the
DPF is recognized as being blocked. Then the PCM stores a corresponding DTC,
illuminates the MIL (Malfunction Indicator Light) and activates the limp home mode.
• The blocking of the DPF is often as a result of excessive soot emission by the engine
(e.g. due to EGR valve stuck open, leak in the intake-air system etc.) or can be attributed
to multiple failed regeneration processes. To rectify this concern, a manual regeneration
should be carried out using WDS (refer to the section “Control System, Service and
Repair”).
01-66 Service Training Mazda6 Facelift
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