DTC Troubleshooting

DTC Troubleshooting: P0443

DTC P0443: EVAP Canister Purge Valve Circuit Malfunction

Special Tools Required

- Vacuum pump/gauge, 0-30 in.Hg, Snap-on YA4000A or equivalent, commercially available

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Initial Inspection and Diagnostic Overview

1. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

3. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.

4. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0443 indicated?
YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the EVAP canister purge valve and the ECM.


5. Turn the ignition switch to LOCK (0), and allow the engine to cool to below 140 °F (60 °C).

6. Disconnect the vacuum hose (A) from the purge valve (B) in the engine compartment, and connect a vacuum pump/gauge, 0-30 in.Hg, to the hose.

7. Start the engine, and let it idle.

Is there vacuum?
YES - Go to step 8.

NO - Go to step 14.






8. Turn the ignition switch to LOCK (0).

9. Disconnect the EVAP canister purge valve 2P connector.

10. Check for continuity between EVAP canister purge valve 2P connector terminal No. 2 and body ground.

Is there continuity?
YES - Go to step 11.

NO - Go to step 23.






11. Jump the SCS line with the HDS.

12. Disconnect ECM connector B (44P).

13. Check for continuity between EVAP canister purge valve 2P connector terminal No. 2 and body ground.

Is there continuity?
YES - Repair short in the wire between the EVAP canister purge valve and the ECM (B3), then go to step 24.

NO - Go to step 30.






14. Turn the ignition switch to LOCK (0).

15. Disconnect the EVAP canister purge valve 2P connector.

16. Turn the ignition switch to ON (II).

17. Measure the voltage between EVAP canister purge valve 2P connector terminal No. 1 and body ground.

Is there battery voltage?
YES - Go to step 18.

NO - Repair open in the wire between the EVAP canister purge valve and the No. 3 ALTERNATOR (10 A) fuse in the under-dash fuse/relay box, then go to step 24.






18. Turn the ignition switch to LOCK (0).

19. Jump the SCS line with the HDS.

20. Disconnect ECM connector B (44P).

21. Check for continuity between ECM connector terminal B3 and EVAP canister purge valve 2P connector terminal No. 2.

Is there continuity?
YES - Go to step 22.

NO - Repair open in the wire between the EVAP canister purge valve and the ECM (B3), then go to step 24.






22. At the valve side, measure the resistance between EVAP canister purge valve 2P connector terminals No. 1 and No. 2.

Is there about 25 Ohms at room temperature?
YES - Go to step 30.

NO - Go to step 23.






23. Replace the EVAP canister purge valve. Service and Repair

24. Reconnect all connectors.

25. Turn the ignition switch to ON (II).

26. Reset the ECM with the HDS.

27. Do the ECM idle learn procedure. ECM Idle Learn Procedure

28. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0443 indicated?
YES - Check for poor connections or loose terminals at the EVAP canister purge valve and the ECM, then go to step 1.

NO - Go to step 29.


29. Monitor the OBD STATUS for DTC P0443 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 28, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the EVAP canister purge valve and the ECM, then go to step 1. If the screen indicates EXECUTING or OUT OF CONDITION, keep idling until a result comes on.


30. Reconnect all connectors.

31. Update the ECM if it does not have the latest software, ECM Update or substitute a known-good ECM. Initial Inspection and Diagnostic Overview

32. Start the engine, and let it idle.

33. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0443 indicated?
YES - Check for poor connections or loose terminals at the EVAP canister purge valve and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 32. If the ECM was substituted, go to step 1.

NO - Go to step 34.


34. Monitor the OBD STATUS for DTC P0443 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. Service and Repair If any other Temporary DTCs or DTCs were indicated in step 33, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the EVAP canister purge valve and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 32. If the ECM was substituted, go to step 1. If the screen indicates EXECUTING or OUT OF CONDITION, keep idling until a result comes on.