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Home >> Volvo >> 1995 >> 850 Base, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Turbo >> Diagnostic Trouble Code Testing >> MOTRONIC 4.3 Control System >> Code 2-4-1: EGR System, Flow Malfunction

Code 2-4-1: EGR System, Flow Malfunction

  1. Turn ignition on. Use Volvo Scan Tool (998-8686 ) parameter Diagnostic Test Mode No. 3 and check EGR controller functions. If EGR controller operates, go to next step. If EGR controller does not operate, go to step 7).
  2. Turn ignition off. Disconnect wire at EGR controller connector terminal No. 2. Connect a jumper wire between EGR controller connector terminal No. 2 and ground. Start engine and run at idle. If engine runs unevenly at idle, fault is intermittent. Go to step 11). If engine does not run unevenly at idle, go to next step.
  3. Turn ignition off. Carefully remove White hose from EGR controller. Connect vacuum gauge to White hose. Start and run engine at idle. If vacuum gauge gives any reading, go to next step. If vacuum gauge does not give a reading, ensure White vacuum hose and connection to intake manifold are not blocked.
  4. Start and run engine at idle. Connect White hose to EGR controller. Carefully disconnect Yellow hose from EGR controller. Connect a vacuum gauge to EGR controller connector. Connect loose wire on EGR controller to ground so as to open EGR controller. If vacuum gauge gives any reading, go to next step. If vacuum gauge does not give a reading, retest using new EGR controller.
  5. Turn ignition off. Carefully disconnect Yellow hose from EGR valve. Check Yellow hose for leaks or obstruction. Repair as necessary. If hose is okay, go to next step.
  6. Turn ignition off. Connect Yellow hose to EGR valve. Connect vacuum pump to Yellow hose at EGR controller. Start engine and run at idle. Pump vacuum to maximum of 4.35 psi (30 kPa). Check that EGR valve retains vacuum. Engine should run unevenly when vacuum pump shows negative pressure. If engine runs evenly when vacuum pump shows negative pressure but vacuum pump loses vacuum, test using new EGR valve. If engine runs smoothly at idle when vacuum pump shows negative pressure and vacuum pump retains vacuum, check if EGR pipe is clogged. Repair as necessary. If EGR pipe is okay, retest using new EGR valve.
  7. If EGR controller does not operate, turn ignition off. Disconnect EGR controller connector. Turn ignition on. Connect voltmeter between EGR controller connector terminal No. 1 and ground. If battery voltage is present, go to next step. If battery voltage is not present, check wiring between EGR controller connector terminal No. 1 and main relay connector terminal No. 3 for an open circuit.
  8. Turn ignition off. Disconnect EGR controller connector. Disconnect ECM connector. Connect breakout box to ECM connector. Reconnect ECM. Connect ohmmeter between breakout box pin No. 40 and EGR controller connector terminal No. 2. If ohmmeter reads zero ohms, go to next step. If ohmmeter does not read zero ohms, check wiring between EGR controller connection terminal No. 2 and breakout box pin No. 40 for an open circuit.
  9. Turn ignition on. Disconnect EGR connector. Connect voltmeter between breakout box pins No. 40 and 42. If voltmeter reads less than one volt, go to next step. If voltmeter does not read less than one volt, check wiring between EGR controller connector terminal No. 2 and breakout box pin No. 40 for a short circuit to voltage.
  10. Turn ignition off. Ensure EGR connector is connected. Turn ignition on. Use Volvo Scan Tool (998-8686 ) to check if EGR controller functions. If EGR controller functions, code was caused by poor contact in control module and/or EGR controller connector. Repair as necessary. If EGR controller does not function, retest using new EGR controller.
  11. If fault is intermittent, check EGR controller connection and ECM connectors for signs of loose connection and contact resistance. Check wiring between EGR controller connector terminal No. 2 and ECM connector terminal No. 40 for an intermittent open circuit. Also check wiring between EGR controller connector terminal No. 1 and main relay connector terminal No. 3 for an intermittent open circuit.
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