P0401, P0402
Read the instructions below then
start the fault diagnostic procedure.
Symptom: CHECK ENGINE lamp on.
Loss of performance.
Limp home.
P0401
EGR Flow too Low.
P0402
EGR Flow too High.
Fault symptoms
Conditions
Diagnostics are active up to 2250 rpm.
The following conditions apply for the DTC in question:
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P0401:
The exhaust gas flow through the EGR valve has been 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 exhaust gas flow 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
The DTC indicates a mechanical fault. Leakage occurring anywhere in the intake sytem and vacuum system can generate a DTC.
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P0401:
DTC indicates an air leak between the turbo and intake manifold.
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P0402:
DTC indicates an air leak between the mass air flow sensor and turbo (including crankcase ventilation hose).
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A defective mass air flow sensor can generate both diagnostic trouble codes. The diagnostic tool can be used to adjust the EGR control up and down.
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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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