I disconnected batteries to clear the code, it worked for 50 miles or so, then p0402 came back, excessive egr flow. Fordpass says my air filter may be clogged, but its brand new

 

My take on excessive egr flow is it’s either a stuck egr valve, a clogged scr/dpf or a defective exhuast back pressure sensor.


the way the system works is that egr flow computations are made based on changes to mass air flow sensor …when egr valve opens…mass air flow drops….when egr valve closes…mass air flow increases. Sensor that need to work correctly are mass airflow, exhaust back pressure, map .

so if your exhaust back pressure sensor is under reporting pressure..the pcm will compute ever flow as high .

 

all of this makes sense. I’ve replaced the map. Easy enough to replace the maf and the exhaust back pressure.

I did a little searching but having trouble finding part number for maf, especially the exhaust pressure sensor. What are they? Do I need to run motorcraft or can I run autozone equivalent

 

Here’s some data

engine was warmed up good with 30 minutes high way driving.

the screen shots have exhp1 which is exhuast back pressure at the manifold to the passengers side of the turbo. Then you have the rpm. Map data is here.

i replaced these sensors becuase i was tired of chasing ghost for intermittent problems and ford wanted 2
months for a diagnostic appt.

after changing the sensors, my problem was solved.

now…i am not telling you what to do….look at the data and decide for yourself.

my opinion is that a clogged or defective exhaust back pressure sensor can result in under reporting back pressure. The pcm takes this info and sets the the valve…and then expects mass air flow to behave a certain way.. if the the is set thinking back pressure is x and it’s really x+, the mass air flow sensor sees not enough air flow drop and declares too much egr flow.

folks can chim in and give different views

it cost me 513.00 to change the map, IAT, mafs , and the ebr using at ford dealership parts.

but before that since I was getting egr errors …I replaced the egr valve..egr valve replacement had no change…then I went back in and looked at the egr by pass valve and it was fine….then seeing no change…I went in and pulled the cooler ..it was slightly dirty but not clogged …cleaned it with degreaser type oven cleaner (not ez off) and poked around the egr tube connection ducts and they were fine. Reassembled. And problem was still there. At this point I was facing a scr, or turbo problem……then I looked at some old screen shoots of exhuast data and noticed the air flow data was way off compared to when the truck was running fine. Changed the sensors and bingo…everything was good.

these trucks are overly complicated due to emissions goals and it does not take much to drive the system crazy.

I would not use auto zone parts or even the so called ford oem online parts. I bought a map sensor and mass airflow and ox sensor online a few weeks ago..the parts had individual ford boxes but they were white boxes with blue letters..the parts I bought at the dealer were white boxes with red lettering …so the online stuff was not genuine ford parts.

here’s the data …good luck

also, note the data is with dpf SL of 15, numbers will be different if dpf has more soot in it.

 

All of this makes perfect sense, thank you!

Ya I was watching the EGR command vs actual on my tool and they "looked" pretty good so I didn't think it was an EGR, but instead some controls logic issue based on sensors. Internet tells me replace map, I did, so now I'm going to replace everything and order those parts. Thank you so much for the help here. I'm going to work on this and report back after I get parts and find time to fix myself. I don't want to be the guy that doesn't respond so I'm crossing my fingers I end up doing this work and then report back saying something as simple as "if you have dtc P0402, start here: . . . . . . ."
On a side note, I've been thinking about getting the banks derringer and display, you happy? If I can get the DTC to clear, ill do this next

 

so here’s my take on these kind of toys …in moderation it’s probally a good thing

derringer has 2 thru 6 range and about 10hp gain each per setting..but…it will generate more soot…and….since it taps into the map..it starts to narrow your map out of tolerance range. Put it on 6, and drive in the rain, you’re going to get a p0069 which is manifold pressure …this is caused by the narrow tolerance and the steam from the rain.

idash is safe and can’t hurt anything


pedal monster …this will increase trans clutch plate wear..if you do a tranny drain and fill about 5k miles after installing a pm your tranny fluid will be black and smell burnt. There is a setting to do a slow pm engagement and I have mine set to kick in at 10mph.

bottom line it’s always a trade of between reliability and performance…..you can’t have both.

 

This advice would be better if you listed the specific online source you think might be selling knock off Ford parts. Are you saying the source calls themselves Ford Oem Online Parts...gotta web address? Genuine Ford parts can absolutely be purchased online, without stepping foot into a dealership. Often times it is Ford dealerships selling online.

 

since your advocating the “on-line”, I think it would be best for you to provide links for a source that you think is credible.

if I put up one or two that is not….that might i
ply that everything else is fine.

not worth relighting a tourch in the blowing wind.


thanks

 

That makes no sense. You made a statement that you ordered parts from an online source that you believe to be fakes. That one source is not an indication that all online sources are selling fake Ford parts. Posting a link to your source would be helpful when making that sort of claim.

You are aware that there are numerous dealerships that sell parts online? How about that Ford has an online site dedicated to selling parts and accessories?

 

Here's an online Ford parts store, that I personally have purchased mirror parts and cablights is all that comes to mind, that came with Ford OEM part numbers in Ford plastic bags, cablights, in boxes with Ford part numbers stickers... The mirror parts also. I'd have zero issues ordering from them.

https://www.villagefordparts.com/v-2...6-7l-v8-diesel

 

Good morning everyone, to get the thread back on track, the original poster was trying to figure out why the p0402 code was set immediately after replacing the intercooler hose. Same question for me. The code was set within 50 miles of replacing the hose. Interestingly my code cleared itself a few days ago which made me happy, but then climbing up a hill it set the code again.

 

this is what happened to me and I kicked the thread back up. Best advice is to replace the sensors listed from the poster who included pictures of his parts. My map was plugged and going to replace others.

 

I've got the SPE cold side hose still sitting in the box, which I haven't got around to installing yet (no rush, OEM hose is still fine). However, it's just the hose, and not the hose + housing. I'm wondering if that makes any difference.

Also, have you reached out to SPE to see if they have any feedback as to the sudden appearance of the code? Perhaps others have approached them with the same issue, and they might be able to provide some insight as to how to resolve the issue.

 

update for me. I had replaced the cold air tube and immediately starting setting the P0402 error code. I finally took it to a Ford dealer.
they said the code was for EGR excessive flow. The code was set because the system was not reprogrammed after replacing the CAC tube that had split open. The technician performed the parameter reset and recalibration procedure and retested.

1 hour of time. no parts.
thanks everyone