Code P0401?

I have the exact same question/problem/error code on the same vehicle. I have changed the EGR, DPFE, and the EGR Control valve. I have checked all hoses and ports for blockages or buildup. Still have the light on and Ford doesn't know what to do.

HELP!!!

I have the same problem!! help

It sounds like it may be caused by the intake being clogged up with carbon deposits, thus not letting exhaust gas back through the intake.

I suggest that you remove the intake manifold, then remove the throttle body. Peel off the throttle body gasket and see if the channel, where the EGR gasses flow into the intake manifold, is clogged with carbon build-up.

I have pulled the throttle body off and cleaned the ports replaced egr valve pressure sensor and solenoid still get service engine light on with the same code p0401 what else can I try.

Have you removed the EGR to make sure it isn't plugged with carbon as well as the intake where it mounts?

Yes I have egr is brand new pulled intake completely off and cleaned ports out where egr bolts up. solenoid, and pressure sensor are new too. Is it possible that tube from exhaust is clogged?

Yes, it is possible.

Sorry it took so long to get back to you I'm going to pull the tube and check it out if not that should i check into the cat. converter or start checking wires to pressure sensor as well as solenoid.

It would be a good idea to check the converter too. If it is good, then I would start tracing wires.

Joe

check engine light shows code.....p0401. just before the egr valve, is a (?) pressure sensor, what are the odds that this needs replacing ? thanks, beans

[quote:19af07dcc3="WM. COGGESHALL"]Engine Mechanical problem
1999 Ford F150 6 cyl Two Wheel Drive Automatic 105000 miles
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CHECK ENGINE LIGHT SHOWS CODE.....P0401. JUST BEFORE THE EGR VALVE, IS A (?) PRESSURE SENSOR, WHAT ARE THE ODDS THAT THIS NEEDS REPLACING ? THANKS, BEANS[/quote:19af07dcc3]

There is a seperate code for the sensor. Take the EGR Valve off and Clean it.

Code Definition

P0401 Exhaust Gas Recirculation Flow Insufficient Detected.

also alot of times i find that sensor, dpfe fails alot too if cleaning the egr doesnt work. they have updated the part from the metal one to now a plastic one.

Hi, a few weeks ago I was getting a rough idle, revving on idle and rough acceleration. It came after a bit too long between an oil change. I added oil, but my dipstick showed almost none. My check engine light was giving me p0401, so I swapped my EGR valve, then DPFE and then tested my vacuum solenoid. Everything checked out, and the check engine light turned off, but the rough idle and rough acceleration are still there around 40 mph to 50 mph.

Now, there was an air leak, so I swapped the hose attaching to the throttle body which cured the idle revving with a good looking one from a junk yard, same model. I also cleaned the throttle body, sprayed carburetor cleaner in the EGR tube and shoved wire brushes in the small ports to clean it out. I swapped seven of the eight spark plugs (#4 has a piece of tape stuck to it, and the socket won't seat) , and then tested the front four plugs while running to see if wires and coils were still good. They checked out. I put two rounds of fuel injector cleaner into my tank, on separate occasions but it didn't change the outcome. It runs fine while cold, but once it's warm it gives me the roughness.

Okay, I've got two problems. 1. I've got a spark plug I can't get out because of the tinniest piece of tape in the way from the socket wrench seating properly. This plug is also the one hardest to reach, and I'm at a loss of how to get it out. I found out using a mirror and a specially rigged head lamp. 2. my rough acceleration has turned into check engine light flashing on and off while driving. Today, my engine shut off entirely after driving it to AutoZone and plugging in the obd2 scanner. I am assuming it's check engine light flashing from unburned fuel getting into catalytic converter but I can't solve the misfire problem. Suggestions on what to try next?

Hello,

Can you pull the Direct Trouble Code (DTC) from your Data Link Connector (DLC) for me again, please? When your Malfunction Indicator Lamp (MIL) or "check engine" light is on and flashing, this means that you are having a catalyst damaging event. There are two types of misfires, Misfire A and Misfire B. Misfire B is a small misfire. Yours is a Misfire A, which needs to dealt with immediately. Please get back to me with the DTC, and we will go from there.

Thanks,
Alex
2CarPros

Alex, when I tried to pull the code it stopped registering a code because the engine shut off and I had to restart the battery with a jump start. I don't have a scanner, I've been driving to AutoZone to borrow theirs.

One more thing; I was testing the TPS and I noticed it was giving bad readings so I changed that as well, a brand new one.

You would need an advance scanner to read mode6 data. Ford is not very good at throwing misfire codes. Mode6 data will tell you which cylinder is actually misfiring. If the AutoZone scan tool can read that data let us know and I can guide you into what you need to read on the misfire monitor to try and pin point the cylinder misfiring.

To me it sounds like you could have a bad coil under load which is very common. Mode6 data will show us if you have a cylinder misfire. Let us know what the scan tool is capable of doing so we can guide you.

Hello again,

Okay, I would recommend not to drive if at all possible. This is a class A misfire and is very serious for the longevity of your engine. To give you a personal experience I own a 1997 Ford Mustang GT. I installed a Vortech V1 supercharger on it and instead of reflashing the ignition and fuel maps of my PCM, I decided to run a fuel management unit. The FMU's work great, as boost increases it squeezes the fuel return line and effectively ups the psi of the fuel rail 10 psi for every lb of boost. The only thing is they depend on a vacuum line to work and if something happens to that vacuum line when you are under boost, your engine will go extremely lean, and "poof", no more engine. Well when doing a third gear pull, at about 135 mph and 5,500 rpm's, the vacuum hose blew off the FMU. My MIL instantly came on and starting flashing with a dead miss. I was able to baby it home four miles away and park it in my garage. A Misfire A, catalyst damaging event. I am not saying this is going to or is what is going on with your engine in any way, but here's what happened to mine. An eighth of my #4 piston was gone, connecting rod torqued and bent with a hairline fracture right done the shaft (Thank God) it stayed together. You could literally look down through the top of my #4 piston at the connecting rod. This is a Misfire A. Yours probably isn't this serious, but it must be fixed or it could wind up like this. You can pick up a basic code reader on Ebay or Amazon for around $20.00. Anyway, please get the code for me. Maybe they can rent you one with a refundable deposit? We can go from there.

Thanks,
Alex
2CarPros

Does the "Check Engine" light clear itself when correct repairs have been made on a old 1996 obd2 system? I would like to avoid clearing the code manually because then I have to deal with P1000.

Okay, the AutoZone scanner is not capable of showing Mode 6 data. I did find one on Amazon that says it can show ob2 enhanced mode 6. Would you check out this link and make sure I read it right? It's at the bottom of the page

XTUNER AM1011 OBDII/EOBD Plus Car Code Reader OBD2 Scan Tool Engine Code Reader Automotive CAN OBDII Diagnostic Tool Update Online https://www.amazon.com/dp/B07P4337N5/ref=cm_sw_r_cp_apa_i_ozzSCbQB9AYNZ

I think it will arrive the fastest and is the best price for an ob2 with mode 6. Thanks for clarifying JIS001 and Alex.

Hello,

There are two ways to clear the Direct Trouble Code(s)(DTC)(s) and turn off the Malfunction Indicator Lamp (MIL) on any OBD2 equipped car, from 1996 to present. The first is to clear the DTC with a scan tool. This is the preferred method. The second, and less preferred method, is to simply unhook the negative battery terminal for at least 5 minutes. This will wipe out the Keep Alive Memory(KAM) in your vehicle's Power-train Control Module (PCM) or "computer", which is where the DTC(s) are stored. In the diagrams down below I have included the factory diagnostic troubleshooting guide for your vehicle for DTC P1000. Please go through this guide, so you can turn your vehicle's MIL off, and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Okay, Alex, I realized based on your definition of flashing check engine light that I needed to learn how one might define it. Using these definitions, my cars check engine light only turns on and off intermittently while driving 40 to 50 mph. In the short term, I will not drive it until we solve the problem.

Intermittent
Sometimes, the problem comes and goes. This is referred to as an intermittent or soft failure and can cause the light to flash, stop flashing, and then start again. The problem appears only when certain conditions appear. For example, the loose connector or broken wire that keeps connecting and disconnecting when the vehicle travels over bumps or irregularities on the road, causing the light to turn on and off for periods at a time.

Continuous Flashing
When the check engine light flashes continuously, it means you have a critical problem that will cause serious damage if neglected. Usually, this originates in a misfire that allows fuel to pass into the exhaust manifold and down to the catalytic converter where high temperatures ignite the fuel. Eventually, this condition will damage the exhaust system or catalytic converter. You need to fix the problem soon before a minor repair turns into a major and expensive one.

Good afternoon,

If your repairs are successful, they will clear after 50 key starts with no continuing issue.

The most common failure is the EGR pressure sensor.

Roy

Looks like it does. I am surprise that scanner is so cheap? I might order one myself?

oh, wow. I cannot wait 50 key cycles. I replaced the EGR Vacuum Regular solenoid and DPFE sensor and I am still having this issue. Do you have the pin layout and voltages in/out to these sensors?

Okay, a couple of updates. I noticed that a coil plug came out of its socket slightly. I'm not sure if the screw threads are stripped, but I tightened it back down and the majority of the roughness is gone. There's still some rough bumps though, one at idle, and another at 40-50 mph. This also solved the random dead battery issue.

The scanner came in, no stored DTC codes or pending codes but probably because I need to drive it around since I've had to jump start the truck. What type of data should I share?

DPFE sensor is the EGR pressure sensor, correct?

Hello again,

I am glad to hear you got it straightened out. If your cose reader is capable of reading pids I would want to look at SHTRMFTB!, SHTRMFTB2, make sure that O2B1S1 Voltage is switching between 0.1Volts and 0.9Volts, same for O2B2S1. If not if you drive it 2 times for me with a 10-15 minute break in between drive cycles, making sure to bring it up to temperature. Send us any DTC(s) that illuminate the MIL.

Thanks,
Alex
2CarPros

Correct.

Were the hoses to the DPFE melted?

Roy

I would also look at Mode 6 data as well and look for test ID 53. See image below. If that information is available it will be a lot of help. When your in Test ID 53, take a pic of All the component ID'S and post them on here.

Before you do that, make sure you have a good battery because a week battery will cause the data to clear. If the battery is good drive the truck to make the condition you are describing appear. Do that for a couple of miles. Once you get home, let it idle and then scan it for codes and look for mode 6 on your scanner and test I'd and take pictures of all the component ids. Let us know please.

The hoses to the DPFE are not melted.

I will try and check these sensors and report back in a few minutes.

Hi Alex,

Okay, I think you are onto something. I took three readings, 1) one cold just for reference, 2) one warmed but idling and 3) one while the car was driving 60mph.

Okay, so these readings are at warmed and idling (2).
Shrtft1 -. 8
Longft1 4.7
Shrtft2 - 2.3
Longft2 . 8

There are 3 photos of the other data, just for reference.

Sounds good.

Roy

Here's 1 of 3

I manually cleared the code, drove the vehicle, the code is back.

The DPFE and the EGR is brand new.

I unplugged the connector from the DPFE, while the vehicle was on and checked the voltages: First pin 5v, middle pin 0.082v, the last pin 5v.

2 of 3

The voltages are correct.

You need a advanced scan tool to monitor the signal village while the engine is running.

Roy

3 of 3

How advance? i have a Innova 3040e (https://www.innova.com/en-US/Product/Detail/3040e)

Eff, you need this 4th photo too.