1997 Mercedes Benz SL600FACTORY OEM SERVICE PROCEDURE

Testing Procedure

NOTE: For ME-SFI control module location and identification, see ME-SFI CONTROL MODULE CONNECTOR IDENTIFICATION  .
  1. Actuation -  Connect DVOM between left cylinder bank ME-SFI control module connector 1 terminals No. 13 and 25 (socket box terminals No. 13 and 25). 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 left cylinder bank ME-SFI control module (N3/11).
  2. Current Consumption -  Turn ignition off. Connect ammeter between left cylinder bank ME-SFI control module connector 1 terminals No. 26 and 13 (socket box terminals No. 26 and 13). Turn ignition on. Ammeter should indicate 0.6-3.4 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 left cylinder bank ME-SFI control module (N3/11). Repair as necessary.
Chapter Navigation
Return to Chapter: DTC P0155: O2 Sensor Heater Of Left O2 Sensor Upstream TWC (G3/3)
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.