V6 Acura and Honda having problems with EGR trouble codes P0401, P1491, or engine ping
Acura and Honda’s with V6 engines, with EGR trouble codes and/or engine pinging. Check engine light on with DTC’s PO401 (insufficient EGR flow) or P1491 (insufficient EGR lift), This problem is due to the EGR port being clogged causing the failure. Honda has issued a TSB (Technical Service Bulletins) TSB-99-085 for the corrective action for cleaning the EGR port, and installing new EGR pipe kit. APDTY has also released a similar solution for unclogging and replacing the EGR port tube.
Corrective Action for Cleaning the EGR port, and installing the EGR Pipe Kit
1998-00 Accords V6 – ALL
2001 Accord V6 – 4-door from VIN 1 HGCG 1…1 A000001 thru 1 HGCG1…1 A058564
2001 Accord V6 – 2-door from VIN 1 HGCG2…1 AO00001 thru t HGCG2…1A023388
BACKGROUND: In some areas of the U.S., certain basic chemical properties of gasoline (regardless of brand) may cause the intake manifold EGR port to clog or the EGR valve to fail. If this happens, the MIL comes on with a DTC P0401 (insufficient EGR flow) or P1491 (insufficient EGR lift) stored.
1. Remove the throttle body cover, intake manifold covers, ignition wire holder, and ignition wire cover.
2. Disconnect the brake booster vacuum hose and the vacuum hose from the intake manifold
3. Remove the throttle body from the intake manifold (two nuts and two bolts). Leave all hoses, cables, and electrical connectors connected to the throttle body. Discard the throttle body gasket.
4. Remove the PCV valve from the cylinder head cover. Remove the intake manifold (three nuts and six bolts).
5. Remove the intake manifold chamber, IAT sensor, boost plate, and PCV hose from the intake manifold.
7. Use a 8-mm drill bit and carburetor cleaner to clean the EGR port in the intake manifold. Turn the drill bit only by hand. Do not use a power drill.
8. Put the special drill bit from the EGR pipe installation kit in your power drill. Coat the drill bit completely with clean engine oil. NOTE: The oil coating is critical to drilling the hole accurately, and it contributes to drill bit life.
9. Insert the guide part of the drill bit into the EGR port. Make sure it is inserted fully. Then drill out the EGR port using steady pressure on the drill Make sure the port is drilled through completely.
10. Clean up the aluminum Chips from drilling, then remove the duct tape.
11. Put the Manifold in a parts washer (solvent or soap and water) and clean it thoroughly.
• Flush out the EGR port for 20 seconds.
• Flush out the manifold from the throttle body opening. Run cleaner down each side for 20 seconds.
• Flush each intake runner for 10 seconds. Start at the throttle body end and work towards the back.
• Turn the manifold so the throttle body opening is facing down. Flush each main runner for 20 seconds.
• Dry the manifold with compressed air and clean shop towels.
14. Install the intake manifold chamber; torque the nuts and bolts to 12 N•m (8.7 lb-ft). Install the IAT sensor; torque it to 18 N•m (13 lb-ft). Install the boost plate; torque the bolts to 12 N•m (8.7 lb-ft). Install the PCV hose.
15. Inspect the EGR port in the front of the injector base on the engine. If it is partially or fully clogged, clean the port.
16. Disconnect the 6P connector from the EGR valve. Remove the
17. Install the new EGR valve with newly supplied gasket; Torque the mounting nuts to 22 N•m (16 Ib-ft). Reconnect the 6P connector.
18. Install the intake manifold with the original gasket. Torque the mounting nuts and bolts to 22 N•m (18 lb-ft) sequentially in two or three steps. Route the PCV hose so it is not pinched under the intake manifold.
19. Install the PCV valve in the cylinder head cover.
20. Install the throttle body with a new gasket. Torque the mounting nuts and baits to 22 N•m (18 Ib-ft).
21. Reinstall the brake booster vacuum hose, vacuum hose, ignition wire holder, and all of the covers.
22. Connect the PGM Tester (loaded with SN200 or later software). Clear any DTCs.
23. Use the PGM Tester to override two-trip error detection.
• From the PGM tester menu, select 1. Honda Systems.
• Then select 2. SCS.
24. Test-drive the vehicle to make sure no new OTCs are set.