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HOMESERVICE MANUALSAUDI1996A4 BASE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - 2.8LCIRCUIT TESTSDTC P0440/16824 - EVAP SYSTEM MALFUNCTION
1996 Audi A4 Base, Standard

DTC P0440/16824 - EVAP System Malfunction

1996 Audi A4 Base, StandardSECTION DTC P0440/16824 - EVAP System Malfunction
NOTE: PCM uses EVAP differential pressure sensor to measure pressure between EVAP canister and EVAP canister purge solenoid valve with purge solenoid valve open and closed. If difference between 2 pressures is less than .06-.33 psi (4-23 mbar) (depending on air pressure), DTC is set.
  1. Inspect EVAP system for kinks and/or pinched hoses. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
  2. Inspect EVAP system hoses between intake manifold and EVAP canister purge regulator valve, EVAP canister purge regulator valve and EVAP canister, and EVAP canister sensor and EVAP canister. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
  3. Disconnect EVAP canister purge valve electrical connector. Using DVOM, check EVAP canister purge valve resistance. Measure resistance across EVAP canister purge valve terminals. Resistance should be 20-28 ohms. If resistance is within specification, go to next step. If resistance is not with specification, replace EVAP canister purge valve. Erase DTC memory and test drive vehicle.
  4. With ignition on, connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminal No. 1 and ground. Voltage tester should light up. If voltage tester lights up, go to next step. If voltage tester does not light up, check fuse for EVAP canister purge valve. If fuse is okay, go to next step. If fuse was replaced, erase DTC memory and test drive vehicle.
  5. Using a DVOM, check wiring between EVAP canister purge valve harness connector terminal No. 1 and fuse. See WIRING DIAGRAMS  section. If wiring is okay, check fuel pump relay and relay triggering. See SYSTEM/COMPONENT TESTS article. Go to next step.
  6. Connect VAG 1527B voltage tester between EVAP canister purge valve harness connector terminals. Using VAG 1551 scan tool, use OUTPUT DIAGNOSTIC TEST mode, function 03 to trigger EVAP canister purge valve. Voltage tester should flash. If voltage tester does not flash or lights up continuously, go to next step. If voltage tester flashes, ensure EVAP canister purge valve is not mechanically binding. Replace as necessary. Erase DTC memory and test drive vehicle.
  7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
  8. Using DVOM, check resistance between EVAP canister purge valve harness connector terminal No. 2 and test box socket E12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open or short circuit. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING  in this article.
  9. Inspect EVAP system hoses between EVAP canister and throttle body. Repair hoses as necessary. If hoses were not repaired, go to next step. If hoses were repaired, erase DTC memory and test drive vehicle.
  10. Disconnect EVAP canister differential pressure sensor electrical connector. EVAP canister differential pressure sensor is located in right front corner of engine compartment. Turn ignition on. Using DVOM, check voltage on EVAP differential pressure sensor harness connector between terminals No. 1 (ground) and 3 (B+). Voltage should be approximately 5 volts. If voltage is within specification, go to step 14). If voltage is not within specification, go to next step.
  11. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
  12. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 1 and test box socket C2. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING  in this article.
  13. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 3 and test box socket C6. If continuity is present, go to next step. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle. If an open or short circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING in this article.
  14. Using DVOM, check for continuity between EVAP differential pressure sensor harness connector terminal No. 2 and test box socket B16. If continuity is present, circuit is okay. Replace EVAP differential pressure sensor. Erase DTC memory and test drive vehicle.
  15. If continuity is not present, repair open or short in wiring harness as necessary. Erase DTC memory and test drive vehicle.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
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