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Home >> Mercedes Benz >> 1996 >> SL320 >> Repair and Diagnosis >> External Pages >> Different car >> Section 18 (Engine Controls - Self-Diagnostics With Codes) >> Diagnostic Tests >> DTC P0140: Right O2 Sensor Upstream TWC (G3/4) >> Testing Procedure

Testing Procedure

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 Mercedes-Benz SL600, 2001 Mercedes-Benz SL600, 2000 Mercedes-Benz SL600, 1999 Mercedes-Benz SL600, and 1998 Mercedes-Benz SL600. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For ME-SFI control module location and identification, see ME-SFI CONTROL MODULE CONNECTOR IDENTIFICATION  .

O2 Signal -  Connect DVOM between right cylinder bank ME-SFI control module connector 1 terminals No. 40 and 41 (socket box terminals No. 40 and 41). 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 fluctuate by more than 0.3 volts between -0.2 volts and one volt. If voltage is okay, test is complete. If voltage is not okay, possible causes are right O2 sensor (before TWC) heater failure, wiring harness failure or defective right O2 sensor (before TWC - G3/4). To check right O2 sensor (before TWC) heater failure, go to DTC P0135: O2 SENSOR HEATING OF RIGHT O2 SENSOR UPSTREAM TWC (G3/4)  .

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