SERVICE ENGINE SOON Light

[GSpeed]

Hello all. After fueling this evening, I noticed that my Service Engine Soon light was lit. Could bad fuel have caused the light to come on or just a coincidence? If not, based on members experiences, what are some common issues that I might check, that may have caused the condition. I did browse the ENGINE DIAGNOSTIC PROCEDURES thread however, did not see any reference to service light issues. The vehicle is a 2002 Galant ES-V6 with 46000 miles.
Your help and time is appreciated.

[skyhigh90210]

Did that gas cap click more than 3 times? Also go to autozone and get the code read and find out why the light came on.

[4g63lover]

^^ werd. Make sure the gas cap is TIGHT a loose one will trigger the SES.

[airborneparainf82]

like above said... get the code read and then you'll know why its on. it could be anything without knowing.

[RafalGTZ00]

99-03 haynes repair manual states-

-Gas cap not seated or tightened properly.

-OBD-II detected component fault at fuel or emmissons

- Catalytic converter damage loss of engine power

[GSpeed]

Thank you everyone for your time and help, it's appreciated. I checked gas cap and it's fastened correctly. I'm in the process of purchasing a diagnostic tool to find out trouble code(s)(O2 sensor, mass air sensor, vacuum leaks etc).
I thought there may have been a common issue causing the light to have come on with this particular model, which would help to isolate problem. Should I try removing negative battery cable from battery for about 30 seconds, then reattach it. Will that reset car's computer and turn off your check engine light?
How and where would I connect diagnostic tool, under the hood?
Thanks again!

[JDM4G64T]

Thank you everyone for your time and help, it's appreciated. I checked gas cap and it's fastened correctly. I'm in the process of purchasing a diagnostic tool to find out trouble code(s)(O2 sensor, mass air sensor, vacuum leaks etc).
I thought there may have been a common issue causing the light to have come on with this particular model, which would help to isolate problem. Should I try removing negative battery cable from battery for about 30 seconds, then reattach it. Will that reset car's computer and turn off your check engine light?
How and where would I connect diagnostic tool, under the hood?
Thanks again!

OBD-II connector should be under the dashboard on the drivers side.

[GSpeed]

JDM4G64T, thanks for providing the location. Will follow up and post findings.

[GSpeed]

Diagnostic service revealed that problem is O2 sensor(Bank 1, sensor 2, rear) Is installing the O2 sensor an easy DIY project or something more involved?

[6G72gearhead]

An O2 sensor is pretty easy to replace most of the time. Not alot harder than changing one spark plug assuming it isn't corroded in there very bad.

They have two types of O2 sensor sockets. One looks like a regular socked with one side cut out, I don't like those very much and wouldn't recommend them. The one I have looks kind of like a crows foot wrench and works much better than the socket type.

[GSpeed]

6G72gearhead, thanks for the tip! Would anyone have a good source to purchase OEM Mitsubishi sensors? I believe the part numbers are one of the following(not positive until I pull old sensor and see if part number is in fact etched on it)
MD345850 - upstream sensor (3.0 V6, auto) Front?
MD34851 - upstream sensor (3.0 V6, auto) Front?
MD345230 - downstream sensor (3.0 V6, auto) Rear?
I believe there to be 4 sensors installed, with the two rear being the same part.

[youngin3]

If it said efficiency low anywhere that could be your catalytic converter, so I'd check that one again...

[GSpeed]

lavie2k9, you may be right. As per the mechanic, the code could also mean electrical problem however, he says almost all the time it's the O2 sensor. I decided not to have him discontinue diagnostic testing.The replacement O2 sensor is Bosch direct fit 4 Wire, Heated part # 13412 (downstream sensor). I believe it to be Calif., but not positive.

[GSpeed]

Follow up; I have had the rear O2 sensor replaced and Service Engine Soon Light no longer remains on. Please note: The first sensor (BOSCH # 13412, $73.71 shipped) did not have a long enough wire to connect into harness. Had DENSO (#2344656, $98.79) installed, which installed like OEM. Parts were purchased through www.rockauto.com. Great organization to deal with. Both, pricing and customer service were great.

[youngin3]

It's good to hear you got your problem fixed.

My SES light came on tonight actually. Speak of the devil.

I really hope it is something simple. Last time it was my catalytic converter efficiency low. I cleared it and it has been a good 5K miles since. I hope it's not that. I don't have the money to buy a new cat.

[greddy]

It's good to hear you got your problem fixed.

My SES light came on tonight actually. Speak of the devil.

I really hope it is something simple. Last time it was my catalytic converter efficiency low. I cleared it and it has been a good 5K miles since. I hope it's not that. I don't have the money to buy a new cat.

good luck with that, cheapest I've found a cat was 450. If it is the cat, you could always just get a test pipe :)

[youngin3]

The code was Catalyst Efficiency Low Bank 1. :(

I cleared it and am hoping it is not coming back.

What do you mean by test pipe? I am out of the loop I guess...