I was on my way home right now and the service engine soon light came on.

What can cause this? Thanks

 

Did you recently fuel up, make sure the fuel cap is closed all the way.

 

Yea i fueled up all the way just last night...i opened the cap and cleaned it up and gave it a few clicks to make sure it was closed properly...the light is still there though

Could it be anything else?
Even if its the fuel cap, does the light go off immediately when i tighten it? some suggest i have to disconnect my battery

 

IIRC there is a reset procedure but I don't remember....
It'll reset itself after about 8 engine starts/stops.

 

^ I think so too. Some of those sensors are just too sensitive.

 

When it happened to me all I did was unhook the battery leave it for about half hour and plug it back in.

 

Thank god it went off.

Alright guys, most of you already know this, but for the few who dont; here's how to reset the whole ECU to first when the car came out. This procedure also has a reputation for turning off the SES (Service Engine Soon) light, if it has came on.

I'd definetly recommend you do it if you havent done it yet, or if you have not done it for a long time.

You'll see major performance improvements. The ECU tries to learn how you drive and based on how you drive it will adjust settings, but this adjustment is not actually to our benefit.
After i just reset the ECU the engine and shifting is so much smoother you'll feel the difference right away - especially for the older models.

I've got around 9,000K's on the engine and i still felt the difference after the reset.

Here's how to do it.

It took me about 10 tries to get it, so dont be disappointed if you dont get the blinking SES light the first try.

G35 COUPE 5AT/6MT ECU 1 RESET

1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON and wait at least 2 seconds.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Turn ignition switch ON and wait at least 2 seconds.
5. Turn ignition switch OFF and wait at least 10 seconds.


G35 COUPE 5AT/6MT ECU 2 RESET (The actual Reset is done here)

1) Turn ignition on, wait 3 seconds
2) Push fully and release the gas pedal 5 times within 5 seconds
3) Wait 7 secs, fully push gas pedal and hold for 10 seconds until the SES light (Service Engine Soon) starts to blink
4) Release gas pedal (you are in diagnostic test mode 2)
5) Press and hold gas pedal for more than 10 seconds. Release pedal.

This reset does absolutely no damage to anything, its completely safe.

Timing is extremely critical, if you're off by a second it wont happen.

If you have any modes added to the car, the ECU reset is a must for you.

Happy Driving!

 

IMHO, the ECU reset only works for a short period of time on any noticeable performance change. Disconnecting the battery for 12 hours is much easier for me than messing around with the timing and frustration. I did it a few times and then stopped wasting my time for the temporary gain. To fix an SEL it's great.