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I’m working on the 2002 Mitsubishi Lancer’s 2.0L engine trying to make some sense out of the readings I’m getting off my Actron code reader.

First off, let me start by asking if my drive cycles have not been completed, all of them have “inc” in the right hand results column, does it call into question the error codes I have now?  

I’m dealing with EGR and catalyst problems, codes P0403 and P0421.  Actually I have P0403 codes in the scanner twice.  One saying it is “confirmed” and the other says “pending” while the P0421 code also says “pending”.  The manual doesn’t really define what the difference between “confirmed” and “pending” is unless the pending problems haven’t been recorded long enough to be confirmed.

Here’s what I’m getting from the code reader:
Catalyst Mon – “inc”
O2 sensor mon – OK
O2 sensor heater – OK
EGR Sensor mon – “inc”

Error codes –
P0421 – Warm up catalyst efficiency Bank 1 below threshold (I’m assuming this means the first catalytic convertor after the exhaust gas leaves the engine)
P0403 – EGR control circuit – “confirmed”
P0403 – EGR control circuit – “pending”

Freeze Data
P0403 (Mod $00)

I’ve checked the voltage to the EGR solenoid valve and it’s 12 volts which is in the proper range.  I’ve also pulled the vacuum line between the solenoid valve and the one that goes to the actual EGR valve, I then plugged the line to the EGR valve (it had the vacuum on it) and the engine almost died which tells me the EGR valve is working.  I put a vacuum tester on the EGR valve, itself, while the engine was off and pulled a vacuum on it and the vacuum held so the valve’s diaphragm appears to be good as well and I heard the valve shaft move too.  I guess from these results this means the solenoid valve is normally open …?

The Lancer doesn't SEEM to have a DPFE sensor on it to perform the same function as one does on my daughter's F-150 but there is a round red plastic device with vacuum lines going into and out of it that are connected to the trottle body and provide vacuum to the EGR manifold.  Autozone doesn't seem to have this as a spare part and with no wire going to it the device won't provide feedback for exhaust gas flow.

I haven’t gotten to do any trouble shooting with the other trouble code yet but I guess before proceeding the question about the drive cycle needs to be answered before opening that can of worms.

I need to get these codes cleared and the “Service Engine Soon” idiot light to go off permanently so I can get the car sold.  It seems to be a deal breaker for buyers!

Thanks.  

that model as you have stated does not use the DPFE sensor.. it uses the  oxygen sensors to monitor the exhaust stream to tell what the egr is doing..

the round device is the vacuum control valve...  i don't have much on how that works on mitsubishi cars..  i usually use a vacuum gauge..  TEE it into the line going into the EGR valve...  either jack up the front wheels so you will be able to spin them up to speed under power or lay the vacuum gauge on the windshield under the wiper and take the car out for a spin around the block.. get it up to 35 while watching the Vacuum gauge along with the road..   does the EGR get vacuum signal.??? above idle.. when the car is moving.???? it should...

should be wide band oxygen sensors on that model... so they are widely expensive also...  read the message i sent.

you will want to check over at alldatadiy dot com.. look for recalls and TSB titles on that model  see if there was a recall on the cats...

look at the link next to where you log out.. i sent you some info in the private messages.. that might help explain how it works..

what brand and model scan tool did you buy.. i don't recall...

does it display live data stream with the engine running...    will it graph the oxygen sensor voltages..  that is the best way to tell what's going on. but that also requires reading up on reading oxygen sensor graphs..

i can look it up and see it has the ability to graph the oxygen sensor voltages...


if you bought the hf 98614 it does..



get to the O2B1S1 voltage   look on the right side of the display.. you will see a G .. push the ENTER button..  it will change the display..  in graphing mode.. you want to bring the ENGINE SPEED to around 2500.. and hold the pedal ROCK SOLID... no upward movement .. no downward movement.. if the RPMS drift.. thats ok.. don't move the pedal... look at the wave form.. is it displaying a nice clean pattern up to .9 volts and down to .1... up and down up and down...  then slowly roll out of the throttle..  all the way back to idle... take about 30 seconds in doing this.. watch the wave form..

does it stay clean ..  how about at idle...  is it cycling up and down.. from .9 to .1.. again a nice clean pattern...

then you will need to push the exit button once.. get back to the live data screen... get to O2B1S2 do the same test...  this one should be a less changing line.. again.. learning what the oxygen sensor waveforms look like is a learning project..

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there is an option for the buyers...  if they get the car fixed.. its under warrantee for them... if you get the car fixed... when you sell it.. warrantee ends..


i don't have a specific manual on that model.. to look up exact testing..
alldatadiy dot com has it
eautorepair Dot net has it.

there is also a lot of talk about it online.. just google.   2002 mitsubishi lancer P0421 or p0403


oh.. pending or confirmed..

pending means its part way through a test to see if it works or fails.. some tests take 50 miles to complete.. depending on driving conditions to activate the test...

completed shows that the test was completed and failed..  

each time the engine starts it had a bunch of tests that if the speeds are correct. it will self test..
thats what OBD2 is about.. on board diagnostics..   sell testing all the time... when it finds an issue.. it will turn on the check engine light and confuse the owner as to what to do next.. unless they have read the owners manual that points them to take it to a dealer as soon as possible for a wallet contents flushing.. that is.. if its out of warrantee... they pay for everything that is emissions related under warrantee.. and a few sneaky places...  will tell you that its out of warrantee.. and bill both you and the factory...