P0401
Read the instructions below then
start the fault diagnostic procedure.
Symptom: None.
EGR Flow To Low
Fault symptom
On-Board Diagnostics
Type of diagnosis:
Enable criteria:
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Battery voltage should be 10.2-15.8 V.
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P1636 or P1637 should not be detected.
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Rpm changes between two measurements should not exceed a difference of 40 rpm.
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The difference between two injections must not exceed 1.5 mm
3
/C.
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Requested EGR flow: 26-65 %.
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Injection quantity: 3-9 mm
3
/C.
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Intake air temperature: 20-95 °C.
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Atmospheric pressure should be 90-110 kPa.
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These conditions must be fulfilled for 3 seconds before diagnostics run.
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Fault criteria:
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EGR flow: 25% lower than desired for 33 sec.
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Dependents:
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P0072, P0073, P0100, P0101, P0102, P0103, P0106, P0112, P0113, P01403, P0237, P0238, P0403, P0404, P0405, P0406, P1404.
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System reaction to a fault:
OK report:
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Fault criteria not fulfilled.
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Fault handling:
(See section
Fault handling III, other emissions-related components and functions
for more information)
Diagnostic help
Read value:
Target EGR Ratio,
EGR Ratio
The EGR function is switched off after 1 minute of idling (EGR valve closed). As soon as the accelerator pedal is touched, EGR control is reactivated.
See also description of read value under
"Read Values" menu
for more information.
Checking the wiring
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.
