I have a manual 2008 Honda Fit - sport. 136k miles. Great car but it's been idling rough and very low, to the point of almost dying. Finally got an engine code, the P0404. Figured out what the issue was, ordered a part on line, replaced the EGR valve, cleaned the passages. Worked great for 4 days, then started up again. This time I just took it to a mechanics because I got the check engine light again. Mechanics said it was the same code. $500 later, they said the new EGR valve I just put in was faulty, so they put in a new one and it was running fine. Just got home and it's doing the same thing. There's no way I've ended up with two faulty valves. One was $60 and the mechanics was $300. It runs fine when it's cold, but once it warms up, it's a rough idle and dips down to zero, most of the time popping back up, but it did die on my way back. My question is, can it be something else related to the EGR valve, even though I'm getting the P0404 code? I am a single woman and I need my car. I don't know anything about it other than I know where the valve is located. Any and all advice/thoughts would be greatly appreciated! Thanks.

 

This could be a wiring issue between the EGR valve and the ECU. They really should've diagnosed this properly instead of throwing parts at it if they charged you $500

The car should drive fine with the EGR vave fully closed, so you can try just disconnecting to see if it runs better.

 

Hi. Agree. I think they did not diagnose it since I'm having the same exact problem. What's an ECU?

 

ECU = Engine Control Unit = small computer that tells the EGR valve when to open and close, among other things. So there could be an issue with the wires between it and the valve, making it behave incorrectly.

As I mentioned, the car shoud run fine with the valve permanently closed. Mine was fully stuck and it worked perfectly fine, it just probably wouldn't pass emissions. So I would suggest disconnecting it first (just the wiring, keep the valve itself on the engine) and seeing if it runs better.

The other options could be to go back to the service and complain about them not doing their job properly, or get a wiring diagram, multimeter and try tracking down the issue.

 

If valve stuck open disconnection will not do much. the right way is to unbolt the valve, install "the blocking plate" and strap the valve tot he intake runner#1 with solid wire or two large back zip ties. If engine runs better after that someone will have to troubleshoot the wiring; if no improvement noted, the issue is elsewhere

 

The valve's been replaced, so I don't think it can get stuck open without power. Or at least it shouldn't

 

If piece of carbon from improper passage cleaning jams the valve open it will not seal tightly. May not be applicable to this case but good to keep that in mind.