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Discussion Starter #1
Greetings,,,,

I recently purchased a 2003 MITS Lancer ES with 63K miles on it.However after driving it for another 1000 miles the "Service Engine Soon" light came up and remains "ON" while I drive.I took the car to a local mechanic who connected some gadget under the steering wheel and said that there was a problem in O2 sensor .I asked him the criticality about the problem and he said that its a minor problem and I can live with it.
I also observed that this Service Engine Soon light does go OFF at times but most of the time I see it ON .

Can anyone suggest what should i do?
 

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It could be that your pre-cat (first catalytic converter) is bad. There was a recall on vehicle to have the computer reprogrammed. Some cars had incorrect parameters in the Powertrain Control Module (PCM) software which caused the pre-cat to overhead and melt. When the pre-cat melts away to nothing (internal catalyst only) you'll get the Check Engine Light for the O2 sensor.

The code really means that the signal coming from the first O2 Sensor matches the signal coming from the second O2 Sensor.

I would call a dealer and see if your car had its PCM reprogrammed in accordance with recall #EMR-05-001REVII.
 

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!!!!!!!!!!!!!!!!!!!!!!!

Ok, I HAD the same issue. It was the O2 Sensor before the cat, I think its the ONLY one. Took the car to the dealer, they said it was the PO135 B1 S1 Oxygen Sensor, Heater Circuit Fault. Model # MR578634. The dealer wanted $340.00 for the job (part and labor). Now, that is an ABSOLUTE rip off. Me and my friend just ordered a universal O2 sensor (make sure it has the same # of wires etc...) from this site: http://www.carpartswholesale.com/cpw/mitsu...gen_sensor.html
...for 40 dollars... yes, 40 dollars. We installed it just fine. Though the connector was not included, so we cut the old sensor off and soldered the wires. Light is off now, runs fine. I saved 300 dollars. Easy fix. Hope that helps :)


EDIT--- this is major. After you install the O2 sensor, you'll have to clear the codes. Simply remove the main wirings from negative port of the battery terminal, keep it off for about 5 minutes, then put it back on the terminal. The computer is now cleared. But, a heads up: if your car is a stick, make sure its in neutral when you start it up, because when I did (thankfully I had the e-brake on) the car lurched forward at like 6000 RPMs (the computer was just cleared), and if - yeah, long story. Just keep in in neutral, don't let your foot off the clutch. Also, your computer has to "re-learn" what the idol should be set at, so for about a week, the car will idol low, since the computer was cleared, but it will eventually restabalize itself.
 

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Discussion Starter #4
hello,

I got the scan code.Its P0135 which is pointing to O2 sensor.
Can somebody please suggest how to go about it? the mechanic told me that it would cost approx 200 $.

Any suggestion is welcome.
 

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It's for the first O2 sensor, which can be seen when you open the hood and look at the exhaust manifold.

Attached is the entire procedure for diagnosing this trouble code.



You'll need an O2 sensor socket to remove it (they have them at any auto parts store).

Hope that helps.
 

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Under your throttle is a valve that looks like a mushroom and is held on by two 10mm (I believe) bolts. You need a new gasket for it.

When your engine reaches operating temperature, some of your exhaust gasses are rerouted back to your intake to lower combustion chamber temperatures and NOx (or, oxides of nitrogen) particles that are highest just after stoichiometric ratio (14:7).
 

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ok now i need to know just how to remove the egr valve and how do i know if its an electronic one or not?
also would it be just as good if i just cleaned it(if possible) or would it be better to buy a new one?
tx
 

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The removal instructions were included in that PDF I uploaded. All you have to do is pull the hose off, unbolt the two bolts, and the EGR valve pulls right out.
 

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It helps keep your engine cooler by not recirculating the exhaust gasses BUT...it could cause another CEL.
 

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bank 1 sensor 1 is the o2 before the cats bank 1 sensor 2 is after the cats.. bank 1 sensor 1 monitors the engines air/fuel and bank 1 sensor 2 monitors how good the cat is workin.. bank 1 sensor 1 will cause ur car 2 run bad if it is faulty..

and to determine which cat is bad bank 1 would be the first cat bank 2 would be the other cat if the code came up as a catalyst insuffiency
 

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Thanks for the tip on resetting the computer after replacing the O2 sensor.

I just went to AutoZone today and had them read the codes and, as I suspected, it was P0135 - the pre-cat O2 sensor. I replaced it for $75 in about 10 minutes (easy if you have the slotted socket you can borrow from them for free).

After firing the car back up, the dreaded light was still on so I thought I remembered seeing something about this a while back on this forum, signed on and saw the tip about disconnecting the negative ground for at least 5 minutes. Did that and all is good. No light.

I'll report later about whether it comes back on, whether my gas mileage improves or whatever.

THANKS!!!

Todd

:liebe011:
 

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I know this is an old thread, but I need to visit it.

I have the dreaded P0135. I clear it, with my scanner, and it comes back the next key cycle.

I have already had the recall performed... Well, it was performed long before I got my vehicle, back in 2007 @ 34k miles....

I now have 103k on it. I bought it at 94k.

Is this a simple issue of replacing the O2 sensor, or is there a larger underlying issue that is going to nickel and dime me until I swap out everything?


Before replacing the sensor, can I test it? My scanner can read live data, and it displays O2 sensor voltage
 

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You can do a live reading on its output and sent signals. Also you can pull what its actual should be relative to condition set. You can measure it against the other sensor .
 

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<div class='quotetop'>QUOTE (KiT TeUnG 2549 @ Oct 29 2014, 03:05 PM) <{POST_SNAPBACK}></div>
You can do a live reading on its output and sent signals. Also you can pull what its actual should be relative to condition set. You can measure it against the other sensor .[/b]
I know how to read what the scanner says, but what am I looking for exactly? I have no idea... and my scanner can do much more than I realize

I am not looking to circumvent the situation, or mask it... I am looking to why I am having this code, and what I can do to get rid of it. Is it an issue of possibly bad wiring? is it the sensor itself?

I don't believe in the just replace the sensor, as that is seldom the actual fix for anything automotive..... Sure, sometimes sensors do fail, and that is fine, but I am not just going to throw parts at it and hope for it to get better
 
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