I got 0302 EGR System Hi/Low Flow Code today.
I don't know where to start looking for a problem. Did anyone had this code and how did you fix it ?

I cleaned Throttle body and MAF sensor 2 weeks ago but it shouldn't affect EGR system.

Could it be a clogged small egr pipe ? (when I cleaned IACV a year ago I saw that the pipe opening is clogged but I had no codes).

 

Yea start with that pipe on the intake. That is usually the problem. Search around you will find similar posts.

 

bet ya its the egr tube thats clogged.... check that first 4th gens are plagued with that.. iv never seen one that wasn't clogged

 

Its quite an easy project. No more than 5 hours.

 

Can I try to unclog it with coat hanger through IACV hole ?
Also because I recently cleaned TB , could some dirt clog the opening of the egr pipe ?

 

These old threads have plenty of information on this common 4th gen problem:
http://forums.maxima.org/showthread.php?t=372440
http://forums.maxima.org/oldthread.php?t=350528
http://forums.maxima.org/oldthread.php?t=516825&page=2

 

Yep, just had the same code a few weeks ago on my 99 Maxima. My egr tube was clogged. Took about 3 hours to remove the parts and clean out. Purchased both tube gaskets at Advance Auto for about $5.

 

Anyone want to help me out. I recently got this code and I cleaned the EGR tube. It was all clean but now the code is back. What else do I check?

 

With coldish engine idling, reach way down below the TB and push up on the underside of the egr valve to manual open it, you need to stick a finger or two in the big holes on the bottom side, it's all feel, just pretend it's a girl and your going for the G spot. If your engine stalls out when you manually lift the valve open the problem is not guide tube related. If you can't push up on the valve than it is stuck and will require replacement. If it stalls something else is wrong, I can help you diagnose that also.

 

make sure that the intake plenum at the back (IACV) where the big egr tube attaches (at the top of the pipe) is also clear.

 

Hey I just did what you stated and I am sure I got the right thing. It like divided into 2 sections? If I put 2 fingers in there they are split apart. I pushed up on the valve and it went up and the engine idled lower. Hard to describe the sound you know but the car never did die. It sounded as if it wanted to but didnt. So now what?

 

Here is a video I just took to show the idle. Sorry about the music. I meant to turn it off. And yea the camera fell off the steering wheel also but you see what was needed.

Whoops meant to click edit lol I always do that now

 

Anyone got any ideas what is causing this code?

 

My guess is that it not the EGR tube although I think cleaning that has worked for a lot of people. I had the same 0302 code and when I did the manual valve test, the engine would almost stall.
Mine turned out to be that my EGR-BPT valve was bad and not allowing any vacuum signal through. It would be best to try and understand the entire EGR system before you go replacing the valves.

Here are the 3 valves in the system:
-EGR valve (directs exhaust back to the intake through the EGR tube)
-EGR-BPT valve (controls the strength of the vacuum applied to the EGR valve depending on the amount of exhaust backpressure)
-EGRC solenoid valve (an upstream "switch" that prevents the vacuum from going to the other valves depending on certain conditions like low coolant temp)

The vacuum comes from a hose on the top of the throttle body and goes to the EGRC solenoid valve that switches the vacuum on and off. It then goes to the BPT valve that controls the amount of vacuum depending on backpressure. The vacuum out of the BPT goes to the EGR valve which opens and closes controlling the amount of exhaust going back to the intake.
The easiest way to test if it's the EGRC valve it to bypass it and put the vacuum right to the BPT valve. If the diapraghm of the EGR valve doesn't lift by itself when you rev the engine then the BPT valve might be bad or there could be a clog in one of the vacuum tubes.
this is all explained fairly well in the factory service manual. I can email you that section if you don't have it.

JR

 

You stole the words out of my mouth. But for me it was just a small vacuum line on the BPT valve that had corroded horribly.

 

That's the pic from last year after I cleaned IACV. The EGR tube opening looks clogged but I had no codes (0302) until now.