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Home › Mercedes Benz › 2002 › ML320 › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0400: Exhaust Gas RECIRCULATION Malfunction (Functional Chain) › Testing Procedure

Testing Procedure

NOTE: This test procedure is not possible on ML320, E320 4-Matic and E430 4-Matic.
  1. Actuation & Vacuum Control -  Connect DVOM between ME-SFI control module connector "E" terminal No. 5 (socket box terminal No. 61) and ME-SFI control module connector "A" terminal No. 2 (socket box terminal No. 2). Connect water vacuum gauge to EGR valve. Start engine and idle. Allow engine to idle until coolant temperature is more than 140°F (60°C). Voltage should be less than one volt and vacuum should be less than 10 mbar. If voltage and vacuum are within specification, go to next step. If voltage and vacuum is not within specification, possible causes are wiring harness failure, ME-SFI control module (N3/10) defective or EGR vacuum transducer (Y31/1) defective. Repair as necessary.
  2. Current Consumption -  Connect ammeter between ME-SFI control module connector "A" terminal No. 3 (socket box terminal No. 3) and ME-SFI control module connector "E" terminal No. 5 (socket box terminal No. 61). Drive vehicle on a dynamometer at approximately 3000 RPM engine speed. Observe ammeter and vacuum gauge. Amperage should be 0.3-0.5 amps and vacuum should be 80-220 mbar. If amperage and vacuum are within specification, go to next step. If amperage and vacuum is not within specification, possible causes are wiring harness failure, ME-SFI control module (N3/10) defective or EGR vacuum transducer (Y31/1) defective. Repair as necessary.
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