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Home › Mercedes Benz › 2002 › ML320 › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0450: Fuel Tank Pressure Sensor (B4/3) › Testing Procedure

Testing Procedure

  1. Fuel Tank Pressure Sensor Signal -  Connect DVOM between ME-SFI control module connector "D" terminals No. 4 and No. 5 (socket box terminals No. 36 and 37). Connect jumper wire between ME-SFI control module connector "A" terminal No. 3 (socket box terminal No. 3) and ME-SFI control module connector "D" terminal No. 2 (socket box terminal No. 34). Disconnect purge control line to activated charcoal canister at purge control valve (Y58/1). Connect vacuum pump to purge control line. Turn ignition on. Voltage should be more than 2.9 volts. Using vacuum pump, apply approximately 25 mbar to purge control line. Voltage should be less than 2.3 volts. If voltage is within specification, go to next step. If voltage is not within specification, possible causes are voltage supply problem, wiring harness failure, vacuum line failure, activated charcoal canister blocked or fuel tank pressure sensor (B4/3) defective. Repair as necessary. To check voltage supply, go to next step.
  2. Voltage Supply -  Connect DVOM between ME-SFI control module connector "D" terminals No. 4 and No. 6 (socket box terminals No. 36 and 38). Turn ignition on. Voltage should be 4.7-5.3 volts. If voltage is within specification, test is complete. If voltage is not within specification, possible cause is ME-SFI control module (N3/10) defective. Repair as necessary.
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