I just bought a 2004 Mitsubishi Eclipse Spyder GT on Saturday the 29th and on Monday the 31st the service engine soon light came on. I was wondering if anyone knew why it would come on? It has 26,000 miles on it so does it mean its just warning me for the 30,000 miles service? Or do you think theres really something wrong and I should go and get it checked? Because the dealership should've just did a service on the car.

 

id take it back to the dealer and make them check it, if there is something wrong they have to fix it..........

 

My service engine soon light is intermittent. It will be on for weeks, then off for weeks. Sometimes both, for only days. Whats the deal with that? My mech thought it was an O sensor, he changed it, still happens.

2004 Mitsubishi Eclipse Spyder GT

 

This sounds like you have a short. It is possible to have a short in the connector or wires for the O2 sensor and that would cause it to throw the code sometimes but not always.

 

my guess would be that you are having random misfires. The best thing to do would be to bring it to autozone the day it comes on and have the car scanned. If it is a misfire then its most likely that one of the spark plugs is going bad or that one of the spark plug wires are going bad.

it also may get some stupid code like a "lean condition detected" this occurs sometimes when the o2 sensor is going bad but like you said you had that replaced. It may also be something stupid in the system like the EGR valve that is throwing a code.