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Home >> Volvo >> 1995 >> 850 GLT, 4D Sedan, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 2 (Engine Controls - Tests W/Codes - Non-Turbo (A/T) - MOTRONIC 4.4) >> Circuit Tests >> DTC 231 - Long Term Fuel Trim Partial Load Or DTC 232 - Long Term Fuel Trim Idling

DTC 231 - Long Term Fuel Trim Partial Load Or DTC 232 - Long Term Fuel Trim Idling

WARNING: This page is about a different car, the 1996 Volvo 850. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check for other DTCs. If DTC 315 is stored, perform testing on that DTC first. If DTC 315 is not stored, go to next step.
  2. Check status message on Volvo Scan Tool (998-8686 ). If status message reads LOWER LIMIT, go to step 8). If status message reads UPPER LIMIT, go to next step.
  3. Turn ignition on. Connect voltmeter between MAF sensor connector terminals No. 2 and 4. If voltmeter reads .1-.2 volt, go to next step. If voltmeter does not read .1-.2 volt, test using new MAF sensor.
  4. Check for air leakage in intake system. Repair as necessary. If air leakage in intake system is not present, go to next step.
  5. Check for air leakage in exhaust system. If there is no air leakage, go to next step. If there is air leakage, repair as necessary.
  6. Check fuel and residual pressure. If fuel and residual pressure are okay, go to next step. If fuel and residual pressure are not okay, repair as necessary.
  7. Connect breakout box to ECM and check ground connections. See COMPUTERIZED ENGINE CONTROLS in SYSTEM/COMPONENT TESTS article. Reconnect ECM. Repair as necessary.
  8. If status message reads LOWER LIMIT, turn ignition on. Connect voltmeter between MAF sensor connectors terminals No. 2 and 4. If voltmeter reads .1-.2 volt, go to next step. If voltmeter does not read .1-.2 volt, test using new MAF sensor.
  9. Check for air leakage in intake and exhaust system. Repair as necessary. Check fuel and residual pressure. Repair as necessary. If no air leakage and fuel and residual pressure are okay, go to next step.
  10. Remove hose leading to intake manifold from Canister Purge (CP) valve. Connect vacuum pump to CP valve coupling. If vacuum gauge does not show stable vacuum, repair as necessary. If vacuum gauge does show stable vacuum, go to next step. Check engine oil and fill as necessary.
  11. Start engine and run at idle a few minutes. Using Volvo Scan Tool (998-8686 ), go to scrolling values list and note fuel trim value. Disconnect and plug crankcase ventilation. Read off value of fuel trim once again. If value is more or less unchanged, go to next step. If value rises, engine oil is diluted with fuel. Repair as necessary.
  12. Connect breakout box to ECM connector and check grounds. Connect ECM. Check all signals to and from ECM. Repair as necessary.
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