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Home >> Mercedes Benz >> 2002 >> S430 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0155: O2 Sensor Heating Of Left O2 Sensor Upstream TWC (G3/3) >> Testing Procedure
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Testing Procedure

  1. Actuation -  Connect DVOM between ME-SFI control module connector "A" terminals No. 1 and 2 (socket box terminals No. 1 and 2). Start engine and idle. Allow engine to idle for at least 2 minutes after engine coolant temperature reaches more than 176°F (80°C). Voltage should be 11-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, possible causes are wiring harness failure, O2 sensor (G3/3) failure or defective ME-SFI control module (N3/10).
  2. Current Consumption -  Turn ignition off. Disconnect ME-SFI control module connector "A". Connect ammeter between ME-SFI control module connector "A" terminals No. 3 and 1 (socket box terminals No. 3 and 1). Turn ignition on. Ammeter should indicate 1-4.5 amps. If amperage is within specification, test is complete. If amperage is not within specification, possible causes are wiring harness failure, O2 sensor (G3/3) failure or defective ME-SFI control module (N3/10). Repair as necessary.
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