Engine light..

[brent-ralliart08]

"service engine soon" keeps flicking on. i think its because i installed my CAI. Anyone have any permanent solutions besides unhooking the battery? which makes it go away for a couple days then it comes right back on? Let me know asap that. thanks

[oakrdrs187]

You shouldn't get a code for installing an intake. Unless you forgot to connect a vacuum line or the MAF or make sure the clamps are nice and tight and there's no leak.

What's the code?

[M-Rod]

The only proper way to get rid of that light is to diagnose and properly correct the issue. step 1 is finding out what the code is. it may not even be related to your intake.

[brent-ralliart08]

i doubt it would be anything else my car has 33k miles on it. but of course i could be wrong. everytime i bring it in to get checked out the light turns off when the place goes to read it.

[G-spot]

hmmm, sounds like you need spend $75 for your own ODB-II sensor and keep it in te glove box. :)

[DTP]

Shouldn't the code still be pending, even without the hard code?

Find a friend with one, and "borrow" it for awhile :)


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[krazienluv10]

find out what the code is... also what type of cai are you using?

[brent-ralliart08]

injen. CAI

[monnewbie3]

Ya get it diagnosed. Mine is always on to... Has to do with one of the Catalytic converters not getting hot enough.
Don't really care as they'll be gone soon with headers. (Mitsu wanted 900$ to replace the rear header to clear the problem)

[BIG_WILLY_831]

Ya get it diagnosed. Mine is always on to... Has to do with one of the Catalytic converters not getting hot enough.
Don't really care as they'll be gone soon with headers. (Mitsu wanted 900$ to replace the rear header to clear the problem)

That don't seem right I took my car to the dealer for the same reasone code p420 and p421 catalitic heat threshhold or something....its a recall some galants in 04 and some other years were programed with the wrong heat perameters I had my exaust manifolds replaced, my cat, and had my ecu flashed for free but I walked in with the recall papes in my hand I got them off of the TSB on alldata......

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[monnewbie3]

Good to know :)
I'll have to check that out.

Considering the Mitsu mechanic told me I was missing a 02 Sensor and that's what caused the SES light...(I have a cut 02 sensor where the wideband goes when I get my car tuned, to keep er sealed).
But once I told him to check all the O2 sensors on his computer... he said they're all correctly reporting... DUH!
So I just left the shop immediately....Don't want someone looking at my car that have no clue what's going on.

[brent-ralliart08]

weird... its only comes on when i drive on the highway.

[oakrdrs187]

Switch back to stock and see if the problem is still there. If it is it's not the new intake.

[Isaurio]

Is not the intake. What is the code?

[brent-ralliart08]

same shit keeps happening. i got to take it in to get read and it shuts off. it sucks. i gotta go to the Mitsubishi dealer and just have them flash my ecu. just to end the problem. anynone have an idea how much that costs?

[dknight3]

it should still show up as previous code that it threw i believe with a good obd reader

[brent-ralliart08]

when i have time im jsut gonna drive on the highway till it comes on then head over to a shop right after it turns on.

[Isaurio]

the code is a pending code. What it does the computer shows the code so you could see it, but it waits for a new reading from the sensor. if the reading is good and the computer is happy the code should come off. if is bad the code will stay on or will come back on. Mitsubishi wont flash the computer. You will void the warranty since you put the CAI. and they will tell you is a sensor issue. Bigg $$$ for no reason.

I will say is a vacuum leak issue. the source = MAF. The computer is getting a unread air volume. Meaning, there is some extra air not calculated by the MAF. The air is getting in after the MAF.

[oakrdrs187]

^^^Meaning check your clamps. Happened to me once, except my leak was huge and my car wouldn't go anywhere.

[brent-ralliart08]

i finally got that code... po421 ( warm up catalyst) fefficiency bank 1 below threshold. can anyone tell me whats going on.

[oakrdrs187]

Bad Pre-Cat....Most likely anyway. Possibly o2 sensor but unlikely since it's "Below Threshold"

That code means the first Catalytic Converter, one right off the manifold isn't heating up enough to convert toxic exhaust emissions into non-toxic substances. The core or "substrate" has a special coating on it that when heated it reduces carbon monoxide(CO), unburned hydrocarbons(HC), and oxides of nitrogen(NO, NO2, & N2O) to produce carbon dioxide(CO2), nitrogen(N2), and water(H2O).

So basically the pre-cat is bad or one of the oxygen sensors is gone. Either way you should be under warranty. I wouldn't take your car to Mitsu with your new intake though. The may give you a hard time because of it.

[oakrdrs187]

Re-post of the post above. Not sure why. Edited.

[wetamup2k3g]

I got that code a few months ago, I reset the light and waited for it to come back on, I'm still waiting. While it may be on its way out, I want it to do it again so I know. If you still have less than 8 years on your car though, you should be covered, I think that's the mandatory warranty on emission items.


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[monnewbie3]

I also have this code. Resetting the code with the computer doesn't work. I'm betting you got the ralliart? Seems few of our cars have this. Same bank, same side.

My solution: Headers lol (mitsu wanted to much money since it's welded to the manifold)

[brent-ralliart08]

thats crap. yeah no i think the warranty is voided because i got the intake and res delete. so headers? how would this solve the problem. they flash the ecu or something?

[monnewbie3]

thats crap. yeah no i think the warranty is voided because i got the intake and res delete. so headers? how would this solve the problem. they flash the ecu or something?

They have to prove that your mods caused the problems... So ya probably voided if I know the dealers...

Putting headers on your car eliminates your pre cats... so there are no cats except the main... and you stack your O2's so they read properly.. Sooo basically there's no cats to mess up :P

And yes you'll need a tune afterwards since your afr's will be messy.

[Isaurio]

is usually the o2 sensor at that bank. the pre-cat o2 sensor.

[oakrdrs187]

^^^ I changed it and nothing problem still there.

A cheap fix would be to leave the Cat alone and use the fouler trick on the o2 after the first cat.

[monnewbie3]

^^^ I changed it and nothing problem still there.

A cheap fix would be to leave the Cat alone and use the fouler trick on the o2 after the first cat.

Good idea

[Isaurio]

I will only recommend that on the main cat o2 "2nd" on the I4. The precat o2 sensor i will leave it as it is. Since is the one adjusting your AFR at close loop.

[brent-ralliart08]

i hate you engine light.. =[

[unknown_owner]

i finally got that code... po421 ( warm up catalyst) fefficiency bank 1 below threshold. can anyone tell me whats going on.

I have the same code. had it for months now and it seems to be keeping my TCL/anti-lock brakes lights on as well (at least that what the dealer told me). For me, it's the rear cat that has gone bad. Dealer wanted $1300 to replace it and the 2 O2 sensors. I may have to replace the sensors too since I had the light on since last year. (yeah I know bad). I went out and bought a rear direct fit rear cat for a little over $300 but it looks like hell to try and get it in. May have to find a mechanic who can do it.

[brent-ralliart08]

Just got mine serviced. with the code of po421 . they replaced the rear converter? not quite sure what that is. but it was on the back side of the engine apparently. 2 hours later NO CELs =] but that is with a stock intake. im scared to throw my injen back on now

[oakrdrs187]

Do it but check and re-check all of your hoses.

[brent-ralliart08]

im just gonna wait until spring now.. should have some other add ons like exhaust and headers by then.

[Isaurio]

That cool you got the light off. But if you go to the dealer they will change everything. Thats how they make money. It was no need to change the cats. But anyhow is done. I have headers and i'm cat-less no Check engine code or nothing fresh for 2 years. I going to put back a main magnaflow cat back since the exhaust gases are a little strong.

[oakrdrs187]

^ Tell me about it. My pre-cat is gutted, can't stand anywhere near the back of my car.

[stayer]

P0421: Warm Up Catalyst Efficiency Below Threshold (cylinder 1, 4). Most likely sensor died. Sensor must be replaced. Not necessarily buy the original sensor, it is expensive. You can buy a universal sensor Bosch LS-07 № 0258986507 - 36Y. Original Denso sensor, worth $300, Bosch is worth us $35(the Price in Russia, you might have another price).

[stayer]

Replace the sensor is not difficult, it took me 1 hour. I will tell you.

[stayer]

Start disassembly. Remove the heat hood with exhaust manifold unscrewing the 4 bolt on 12. Here they are at the top and set the lambda sensors http://s12.radikal.ru/i185/1004/ec/40a3ea949015.jpg (http://www.radikal.ru)

[stayer]

Loosen the connection. http://i067.radikal.ru/1004/d9/e681767c2f63.jpg (http://www.radikal.ru)

[stayer]

Sensor turns away wrench to 22mm. http://s006.radikal.ru/i213/1004/62/c7ab2a57cb83.jpg (http://www.radikal.ru)

[stayer]

Here are my sensors. http://s003.radikal.ru/i203/1004/e8/f44221762713.jpg (http://www.radikal.ru) As a temporary measure, you can отмочить them in a strong solvent for paints. For some time it will help. But then again lit "check engine". Therefore, it is better to replace.

[stayer]

On the left of the new Bosch. On the right side the old one. http://s41.radikal.ru/i093/1004/fb/962769329254.jpg (http://www.radikal.ru)

[stayer]

Next, you need to refasten the wiring. We should remove the orange wedge of the plug. in the package there is a manual connection of the wires in color. http://s04.radikal.ru/i177/1004/9b/598f76ca6675.jpg (http://www.radikal.ru)

[stayer]

We must make the length that you want. http://s003.radikal.ru/i203/1004/6b/89009955344f.jpg (http://www.radikal.ru) In the directory, front and rear sensors different. But I tell you, they are the same, the only difference between the length of the wire. Assembly in the reverse order. After replacing the " check engine" is not lit. Error P0421 no. Good Luck...

[John165]

Is there any way to confirm dead oxygen sensor before replacing?

In the manual I downloaded, it only showed a trouble shooting chart for the cruise control. Cause I too have po421, Warm up catalyst efficenty below threshold cylinders 1-4.



I

[stayer]

You must log in to the electronic manual. > Fuel.> page. 13A-33> Find the code 0421.>Click on the link on the page. 13A-598 > To Read. But most of the sensor have to be replaced.

[John165]

Thanks man. I forgot to add that mine was a 8G lol and this was the 9G Forum. Anyway I though they would have been the same, but evidently not. After downloading and going to where you said, I was able to find it at Fuel> 13A-194. So Mitsubishi changed the manual. Anyway, your reply helped out alot. I found this thread by searching, cross referencing the code. So now if another 8G owner comes across this thread they will have it and in addition to the 9G owners page numbers you posted. Again thanks for the help.