P0401, P0402
Symptom: CHECK ENGINE lamp on.
Loss of performance.
Limp home.
Cruise Control does not work.
P0401
EGR Flow too Low.
P0402
EGR Flow too High.
Fault symptoms
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Cruise Control does not work.
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Conditions
Diagnosis active up to 2000 rpm.
The following conditions apply for this DTC:
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P0401:
The flow of exhaust gas through the EGR valve is so low that a control deviation of more than 75 mg air/combustion has been present for more than 7.5 seconds.
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P0402:
The flow of exhaust gas through the EGR valve is so high that a control deviation of more than 75 mg air/combustion has been present for more than 7.5 seconds.
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Diagnostic help
Using the diagnostic tool, adjust the EGR control up and down.
The DTC indicates the presence of a mechanical fault. A leak anywhere in the intake system or vacuum system can generate the DTC.
In the event of a fault, boost pressure control is disengaged.
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P0401:
DTC indicates air leakage between the turbo and the intake manifold.
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P0402:
DTC indicates air leakage between the mass air flow sensor and the turbo (including crankcase ventilation hose).
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A defective mass air flow sensor can generate both DTCs.
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Important
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The EGR valve will close after one minute at idling speed. The diagnosis is active during EGR regulation.
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