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Engine code P0402

29K views 25 replies 7 participants last post by  eluebke 
#1 ·
Pulled codes after check engine light has come on. Cleared code numerous times and still returns. Code says excessive EGR flow. Anyone have this issue with an easy solution. Some guys say EGR will be plugged up with carbon, others say mass air flow sensor. Just wanted to get someones opinion that has had this trouble or know the issue before spending some cash. Truck only has 79000kms.:help
 
#2 ·
I had that code when i went to after market af, put a blocker plate[egr] cleared the code did not come back on, now my egr is shut down with the efi live
 
#3 ·
Truck is completly stock, even the air filter. Probably sounds like the egr has to come off and be cleaned al least i guess. I bought a new ac delco air filter and im gonna put it in and clean the mass air flow sensor when i get a min of spare time. Hoping this cheap easy fix might do it.
 
#4 ·
EvancLBZ, Had the same problem, Pulled the EGR out and cleaned it 4 weeks ago. Fun times :) It was about 90% blocked. This was my first time doing it at 92000 miles. Suggest while you have the EGR out just replace the EGR Solenoid (motor). Even after cleaning the EGR I was still getting the P0402 code. I even tested the motor for operation when I had the EGR out, it worked but I was still throwing the code. I just replaced the motor this weekend, hopefully that will be the end of it. Before pulling the EGR have at least 3 cans of cleaner I used B-12 throttle cleaner it works great. Good luck.
 
#5 ·
I had this issue with after market cold air intake and I asked the same question about a year ago. I got back from someone that some of them did throw the code with stock intake so they came out with a calibration update (dealer update code fix). I asked what the code was and he did not know but he ran a repair shop and it sounded like good info. I would try the other suggestions first but keep this in your back pocket.
 
#6 ·
Checked out code on identifix and out of 11 confirmed fixes, 7 of them were dirty mass air flow sensors, a couple were bad egr motors and one was software and the mass air flow sensor. Cleaned the mass air flow sensor this morning and threw in a new air filter. Gonna try this first. Thanks for all the info.
 
#7 ·
I have been having this problem also since it started getting cold here. Once the temp dropped down into the 40's and 50's my engine light would come on just driving down the road at a steady speed. I can not notice any difference with the way the truck performed. I scanned it with the same P0402 code. My only problem is a few days later the light will go out by itself, only to come on again a few days later, sometimes it will be 2 weeks of driving before it comes back on. But it always comes on driving at a steady speed. I just had the light come back on yesterday for the 5th time in the last 7 weeks. For right now I will just keep driving the truck and see how long it takes to shut off again. Is this the same experience others are having? Or does the light come on and never go off until you clear the code yourself?
Thanks
Eric
 
#8 ·
The light comes on and stays until its cleared on my truck. Even after I clear it it might come back in ten minutes or a week. It also seemed to come on when the temp got low as well. Worked excellent all spring, summer and fall this year. After I cleaned the mass air flow sensor, the light hasn't come back yet. Hoping it cured.
 
#9 ·
eluebke, from my experience the CEL light comes and goes. Determined by when you start the truck and if the egr work properly or not. After replacing the egr motor last weekend I have not had a CEL come on at all this week. I'm saying its fixed. Usually I would have got the light by now, once a week off and then on. This weekend project was replacing the Lower Trans cooler line, not too bad of a job.
 
#10 ·
My light has not gone back out since I posted. I think I may try a new air filter and clean the mass air flow sensor. This seems to be the easiest fix to try first. If this doesn't work, how hard was it to get at the egr itself to try to clean it and change the motor for it? I'm really getting sick of looking at the orange engine light on my dash.
 
#12 ·
I just cleaned the MAF, and I am going to go to the autoparts store to pickup an air filter to replace that next. I will replace it in the parking lot and then clear the code and see what happens. They said they have a WIX paper filter and a K&N filter that fits in the OEM box for $30 more. Does anyone know if the K&N could give me troubles with the code. From what I read some people said that the aftermarket filter made it throw the code also. Or do you think this was just the cold air intake that did this?
 
#13 ·
They say that high performance filters such as k&n where you have to oil the filter is hard on maf sensors. The oil will leave a coating on the sensor and it will have to be cleaned. Probably not a huge deal except that the cel will come on telling you there is an issue. From what I have read I would recommend to use the factory ac delco or equivalent filter.
 
#16 ·
What did you clean the maf sensor with. Compressed air isn't enough usually. I used an electrical cleaner but I've also used a low strength brake and parts cleaner. When I pulled this one out the first time I just blew it off and put it back in, cel light right away. Took it out again and washed it with the cleaner and mine is still ok. Yours still could be the egr plugged up. From what I've read most times it's dirty maf sensors. That info is from identifix which is an online resource for automotive shops.
 
#18 ·
I understand trying to do the cheapest thing first but, IMO it really sounds like a EGR blockage and to include the EGR motor is worn out. The EGR cycles at engine start up and operates during crews speeds such as highway driving. I was getting the CEL light on start up. The motor is held on by four screws, it can be replaced without removing the whole EGR. Even though I cleaned the EGR I still had the light coming on until I replaced the motor its been two weeks and no light. In the beginning I also tried different thing to resolve the issue, not until I got off my @$$ and pulled the EGR and cleaned it. The truck runs sooo much better. Do some reading on it before you start, I had to modify a 12 mm off set box end wrench so I could reach the lower bolt of the EGR, tight fit. Putting everything back together went alot faster than the tare down.
 
#19 ·
The oil for the K&N isn't half as bad as carb, brake or parts cleaner is on your MAF sensor. There are a few companies out there that make cleaner especially for the MAF sensor. Screw the EGR, block it and tune it out
 
#20 ·
Strongly reccomend the MAF cleaner, or a good quality electrical cleaner. In a pinch a low strength brake cleaner but not if you can get your hands on MAF sensor cleaner. K and N air filter oil is sticky and coats the MAF sensor which only requires you to clean it, nothing bad. Agreed on the high strength brake and parts cleaner being hard on it. For me, i drove 5 hours today on the highway at 120kph and all is good.
 
#21 ·
I started to look at things a little closer as I am getting ready to pull the EGR valve to try to clean it. As I was trying to find everything, I noticed it looks as if the previous owner installed a blocker plate in to the truck, as I can see the tab sticking out from the flange back by the firewall. I have had this truck for just under 2 years now and never had the problem before. Does this sound right that it is throwing an excessive EGR flow code if it is blocked, or should I start looking for a leak somewhere else. The truck is stock otherwise.
 
#24 · (Edited)
I checked under the hood and the finger stick is there. So are you thinking the the EGR motor failed and is setting the code even with the finger stick installed? Any idea on how much a new EGR motor will cost me. All I can find is on Oreilly and Advanced Auto's web sites is a EGR valve made by BWD, Part # EGR1897. It is the black housing that accepts the electrical plug. When I type in EGR motor nothing shows up anywhere I look.
 
#26 ·
con_fuse9:

I haven't ever resolved it for the last 3 years. By the time October rolls around it starts to happen. As a matter of fact, my light just came back on 2 days ago again. It will go on and off all winter long. Once the weather warms up my light usually stays off no matter how I drive it. I am confused on why this happens, but a local mechanic told me he wouldn't worry about a egr code and it hasn't given me any issues on how the truck runs. So I just get used to seeing the CEL light go on and off.
 
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