Getting the P0401 and P0403 errors on my 02 Lancer .

The car runs great; never skips, stutters, backfires, misses a beat and still gets 28-29 mpg on the freeway.

I normally wouldn't care to fix something that isn't causing issues, but because it's triggering a CE light it won't pass SMOG (even though the emissions are spot on).

Over the weekend I pulled all the hoses running to the EGR Valve and made sure they were all clean and wide open. I even found the one near the end with the "BB size ball" inside it and made sure it was also flowing. I pulled out the EGR and clean the crap out of it (it looks brand new now - regrettable I don't have a vacuum pump to actually test it through).

Anyone else have ANY ideas as to why I'm triggering these P codes or where to check. Any help is greatly appreciated, and if you are in CA, I'l be happy to buy you a

 

I have had the egr insufficient flow come up on my car however cleaning the egr solved this for me. Did you physically lift the plunger while cleaning the egr ot make sure you got it all out? Im guessing you just need to replace that egr valve I would go to a junkyard if it was me. You could start by replacing the vacuum lines there to see it that fixes it.

 

No I didn't lift/depress the valve to clean it. Hindsight I should of when I had it out. It was a pain to get to and put back. I guess I should do that first and possible find a way to check it for a leak before I go and replace the solenoid or anything else.

 

Yes I always start cheap first . It shouldnt be too hard to pull ive taken mine off several times usually under 5 mins to pull it out. Wobbly sockets are gold for this though. Also when reinstalling I put both bolts and the gasket on the valve then slip it in as a whole unit makes it much quicker for the reinstall.

 

Well since I last wrote here is what I have done.

Replaced the entire EGR system (all hoses, solenoid and components attached to the brass behind the engine). Zip tied all hoses where they connect to the system.

I checked and rechecked the EGR valve. I was able to press the valve down and while covering the hose end the plunger stayed in place. Once I released my finger from the hose the plunger released. Typically this would indicate a good seal and proper functionality.

I cleared the ERG P0401 from the system and drove it around for about 10 minutes. The P0401 returned.

At this point the only other thing that I have read on other forums is that I need to replace my ignition coils on top on the engine. If that doesn't work, I'm tempted to "tune" my on board computer to tell it the system is working fine.

ADVICE PLEASE!!!! What else can I possible do to alleviate the P0401 error?

 

Sounds to me then that you may have a break in the harness that controls the solenoid or maybe pins in the clip have been bent or broken. Here are a couple things I found, you may or may not have already tried.

A code P0401 most likely means one or more of the following has happened:

•The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
•There is a blockage in the EGR (tube), most likely carbon buildup
•The EGR valve is faulty
•The EGR valve may not be opening due to a lack of vaccuum
Possible SolutionsIn fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.

•Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
•Clean out the EGR valve and/or tubing to remove deposits
•Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
•Replace the DPFE sensor (with a good quality / OEM one)
•Replace the EGR valve





P0403 - Exhaust Gas Recirculation Circuit Malfunction
OBD-II Trouble Code Technical DescriptionExhaust Gas Recirculation Circuit Malfunction

What does that mean?The Exhaust Gas Recirculation (EGR) system is controlled by a vacuum solenoid. The solenoid is supplied ignition voltage. The Powertrain Control Module (PCM) controls the vacuum solenoid by grounding the control circuit(ground) or driver. The primary function of the driver is to supply ground for the object that is being controlled. Each driver has a fault circuit that the PCM monitors. When the PCM turns a component on, the control circuit voltage is low, or close to zero. When the component is turned off, the voltage on the control circuit is high, or near battery voltage. The PCM watches for these conditions, and if it doesn\'t see the proper voltage at the proper time, this code is set.

Potential SymptomsUsually a fault in the control circuit, will leave no noticeable symptoms other than the Malfunction Indicator Lamp (MIL) illumination. However, if the EGR control solenoid is stuck open due to debris, etc. the code may be accompanied by misfire under acceleration, rough idle, or engine dying altogether.

CausesThe causes for a P0403 EGR code could be any of the following:

Bad EGR solenoid
Excessive resistance in control circuit (PCM controlled ground) due to an open, chafing or damage to the harness
Poor connection at the EGR solenoid harness (worn or loose pins)
Water intrusion at the EGR solenoid harness
Blockage in EGR control solenoid holding solenoid open or closed causing excessive resistance
Loss of supply voltage to EGR solenoid
Bad PCM
Possible SolutionsWith the ignition on and engine off, use a scan tool to activate the EGR solenoid. Listen or feel for a clicking, indicating that the solenoid is operating.

If the solenoid does operate, you'll have to check current draw on the ground circuit. It should be less than one amp. If it is then the problem is intermittent. If it isn't then there is excessive resistance in the circuit and perform the following

1. When it's activated see if you can blow lightly through it. IF you can\'t there may be a blockage causing excessive resistance. Replace EGR solenoid as needed. If there is no blockage, disconnect the EGR solenoid and the PCM connector containing the EGR solenoid control circuit. Using a digital Volt-Ohm meter (DVOM) check resistence between the control circuit and battery ground. It should be infinite. If it isn't, then there is a short to ground on the control circuit. Repair the short to ground and retest as needed.

2. If the solenoid doesn't click as it should, disconnect the EGR solenoid connector and connect a test light between the two wires. Using the scan tool, command the EGR solenoid on. The light should light up. If it does, replace the EGR solenoid. If it does not perform the following: a. Check for 12 Volts on the ignition supply voltage to the solenoid. If it isn't present, inspect the supply circuit for an open, or a short due to chafing or breakage and re-test. b. If it still doesn't operate: then manually ground the EGR solenoid control circuit. The light should light. If it does, repair open in EGR solenoid control circuit and re-test. If it doesn't, replace EGR solenoid.

 

So far I have replaced;

- Vacuum Control Value
- EGR Vacuum Solenoid
- All Hoses

I have removed and cleaned the valve and tested it. It seems to be working properly.

Where is the DPFE? Anyone have a picture for the Lancer. I believe I have also replaced it since I replaced the entire EGR system (excluding the valve).

I have attached pictures of what I have replaced.. just in case the terminology isn't translating.

 

Im starting to wonder if we have a dpfe as I cant seem to find any refrence to it in the fsm. Did you check your harness clips and/or harness itself for possible breaks? This seems the most likely culprit considering the steps you have already taken to resolve this. In response to your other thread about disabling the system check you can use ecuflash and disable this in an evo rom. I am not sure if there has been enough disassembly done in the stock base lancer roms to disable this.

 

Harness? Are you referring to the all brass looking metal that the solenoid bolts too? If so, yes. I replaced it with the new EGR system. The entire package came with hoses and the entire metal harness.

Perhaps I need to run a vacuum/smoke test of the system and look for leaks.

 

In regards to the DPFE, when I did a search just for a replacement part at RockAuto and other places I don't see any reference to it either. "Googling" if as well doesn't produce any references or pictures for the Lancer.

 

I mean the actual electrical plugs that connect to the solenoids in that area. maybe a bent or broken pin in the plug is causing your issue. You have the evap purge solenoid and the egr solenoid both right there.

You could always use the old carb cleaner trick. Spray carb cleaner around all the vacuum lines and listen for a change in rpms. If you find a spot where the rpms raise as you spray then you have a leak in that area. Be careful if you use this method though there is a the remote chance of setting your car on fire lol.
Yeah in wondering in the vacuum control valve is what we use instead of the dpfe possibly.

 

the MAP sensor is used to detect whether the egr is open or not. Its that thing on top of your intake manifold with the harness coming out of it that leads to your injector harness.

 

After last weekend of cleaning, replacing everything and zip tying all the hoses the CEL did NOT return for an entire week. Everything ran as expected. The last night when I was on my way home, I was sitting idle at a signal light and the CEL returned. I shook my head because I knew exactly what it was.

I checked this morning and sure enough the P0401 had returned.

Since I don't have any expensive vacuum test system or "smoke machine" to see where it could be leaking I'm stuck taking it to the family mechanic. Hopefully he can fix it without costing me too much.

Oh well. I guess there are some things that the internet can not fix.

If it wasn't for having to smog the thing I wouldn't care. Does anyone know how long the CEL has to be off and the car driven before it will pass smog? I've head that if I clear the CEL and then have it smogged that it will fail because the system can tell that it was just cleared.

 

Just to test, if I was looking at the engine from the front of the car, the EGR system I know ends at the EGR Valve. Where is the "start" of the EGR system. Perhaps the EGR system is clogged at the start, where it enters the hoses and that it's not able to actually send the emissions into the EGR system to begin with. in the dark.

 

I'm trying to pass smog as well and I keep failing because of excessive Nox. The smog tech told me to check the EGR function. I can apply pressure to the egr valve when the cars idling and it will stumble. The only code I'm getting is one for high idle on the idle control valve. I think because I tried to adjust the idle without unplugging the idle control harness. I'm not getting any kind of suction on the vaccum lines running to the egr valve. I'm getting 12 volts from both egr and vaccum solenoids. But still haven't hooked a 12 volt source to the vaccum solenoid to check its functioning properly. I removed the egr and the carbon deposit really wasn't built up too bad. Still seems strange to me why I'm not getting any kind of egr malfuction trouble code on the diagnostic tool. Did you ever figure out your egr problem?