[Onca]

Hello guys, my first post here 

So, I've been having issues with P0404 error code on my Hyundai i30 FD, 1.6 CRDi, 66 kW. I've found some old threads that were discussing this issue, but can't find a clear solution to this problem, so I was wondering if someone had the same issue quite recently and managed to fix it.

Pretty much the deal is when outside temperature is above 20 degrees celsius, car tends to go into safe mode or "limp mode" where you have decreased engine power and rev limiter set to 3000 rpm. Sometimes CEL comes on when car gets into safe mode sometimes it doesn't.

What I've tried is to open up the EGR valve and it was absolutely filled with deposits to the point where the valve couldn't even move. I've managed to clean everything up, the valve doesn't seem to be sticking, but even after that P0404 still is coming up.

Went to my mechanic he assures me I need to change EGR, but based to replies from other threads based on this issue, the new EGR didn't fix the issue, since the part itself is quite expensive, would like to try other possible options before going for a new EGR. I belive the EGR cooler is in horrible condition as well if EGR was this bad. Should I try taking the car to the other mechanic to take everything off and properly clean it or maybe there is a different thing I should pay attention to?

[The Gonz]

Welcome, Onca.

It's not clear whether after cleaning you're still getting limp mode as well as the error code.
If your problem is only the error code, a mechanic with a more sophisticated code reader should be able to clear it if the EGR is now functioning.

[Onca]

Clearing the error code doesn't help, I cleared it myself with my OBD and mechanic with his more expensive equipment, it comes back almost immediately together with the limp mode 

[Onca]

If anyone is going to run into the same issue, mechanic replaced the EGR valve with the new one (EGR manufacturer is Delphi) and for now the car is running really well, almost seems like it runs even better then before power wise, but maybe it's just placebo effect. I'll keep this updated if safe mode and error code comes up again.

[Onca]

Here is me with the update, bad news I'm afraid, so car has been running fine for about 4 weeks now, but 2 days ago, it went into safe mode again, searched for error codes and P0404 is again the issue here, today CEL also lit up. Maybe EGR wasn't the issue after all (spent 250 euros on nothing  ) . Will try to schedule the service again and will post on the forum if we will manage to resolve this. Bad thing is that I'm supposed to have technical inspection in a week, so this is a very stressful time.

[TerryT]

Here is me with the update, bad news I'm afraid, so car has been running fine for about 4 weeks now, but 2 days ago, it went into safe mode again, searched for error codes and P0404 is again the issue here, today CEL also lit up. Maybe EGR wasn't the issue after all (spent 250 euros on nothing  ) . Will try to schedule the service again and will post on the forum if we will manage to resolve this. Bad thing is that I'm supposed to have technical inspection in a week, so this is a very stressful time.

@Onca. Sorry to hear this, it must be frustrating after spending the money and then the issue comes back.  Re your stress, I might sound a bit folksy old man but whenever car crap happens to me, I stop and think "If that's the worst thing that's ever going to happen to me, Life ain't that bad!  Surprisingly, it helps.

It's nice to see you keeping the forum updated, so many people don't!

[Onca]

@TerryT Thanks for the kind words 

Here is me again with the update, so today I left the car at the mechanic again, we agreed to clean the intake manifold as this is was one of the possible causes for the error code.

Sadly just cleaning the manifold didn't help, he proceeded with cleaning the new EGR was was fitted a couple of weeks ago since it already had in itself a quite a bit of carbon deposits, but even that didn't help. He fitted a brand new EGR again and it was covered under warranty and car is now running as it should.

He explained to me that the EGR has some software issue where it is open too much, it should be open usually around 40% and mine was open almost 100% at full throttle, so too much carbon deposits were forming inside of a EGR and it just died because of it. In case I'll have some problems again we will try to put new software on. I didn't want to bother him too much with questions about which exact software and so on, but yea.

TLDR - another brand new EGR was fitted, software issue causes EGR to be open in too high of % which builds up carbon deposits and kills the EGR. Software update will be required if the issue comes up again. Even though cleaning the intake manifold didn't fix the error code, it should help with EGR lasting longer among other common benefits.

[TerryT]

@Onca.  Thank you for the update.  It sounds like your problem has been identified and fixed.  A good result for you.  Hopefully you won't need any more EGR software updates in the short term.