1999 Isuzu Rodeo P0401

I originally got code 401 and 405, figured I would eliminate the 401 code since it was all EGR issues. Replaced with new EGR valve and the 405 code disappeared, the P401 Insufficient EGR Flow code did not go away????. The engine is running very rough, almost like I am towing a big load type of feel. Has anyone else had this problem and/or fixed it? What else can I do or look for?

Po401 is from clogged passages for the egr system. you have to remove the throttle body to do. this shouldnt make it run rough you may have other problems.

I replaced my IAC valve and it appears to fix the rough idle/running of engine. But still no luck on EGR p401 code. How do I go about cleaning the throttle body? What is the best way to tell if it's clogged passageway?

without a scan tool you cant really.. to clean you remove the throttle body and you will see a tube a couple of inches in the plenum and it will probably be plugged solid so just get a pick or screw driver and start picking. good idea to take the valve off so you can blow through the passage to make sure all is clean

I had the throttle body and fuel injectors cleaned. Tech said it was very dirty buildup but did not notice anything clogged. The p401 code was reset and came back on within few miles. I took it back to shop and now telling me the port pipe from EGR to intake manifold is more than likely clogged. From I can see, the EGR valve is mounted on the intake manifold. I cannot see any port pipe unless it's inside the intake manifold. Only port pipe I see is from EGR to exhaust manifold and doubt that is clogged. Does this sound right? What else can I try?

thats what i said the pipe is in the plenumn you have to remove the throttle body to get to the pipe..if they know where it is and how to do it and you dont understand how to do then let them do it and this problem will be gone.

I took off egr valve, then Once the throttle body was out of way, there was only one port pipe inside intake manifold. It was plugged solid with a hard mudd like feel to it. Several hours picking at it using carb cleaner and long screwdriver, then finally it was cleared. It would of saved time if I had air hose to blow through port once it got looser (but now I know for next time). Went for a short drive, then FINALLY the check engine light went off. Next morning got my emission inspection...passed. Man felt like a giant weight lifted is an understatement. You were right on ...cannot thank you enough!