Service engine soon light

SOURCE: SERVICE ENGINE SOON LIGHT CAME ON YET MY CAR DOESNT MAKE ANY FUNNY NOISES

THE OIL CHANGE INDICATOR WILL NOT CAUSE THE SES LIGHT TO COME ON.THEY MAY HAVE LEFT SOMETHING DISCONNETED NEAR THE AIR CLEANER HOUSING WHEN CHECKING THE FILTER.IF NOT HAVE CODE READ(SHOP/PARTS STORE)

SOURCE: 2003 Lancer the service engine soon light keeps

I can see that you've done the right things, but something is still amiss... Mitsubishi says

A code P0421 may mean that one or more of the following has happened:

• The catalytic converter is no longer functioning properly
• An oxygen sensor is not reading (functioning) properly
• A sparkplug is fouled

Measure the voltage at the oxygen sensor on Bank 1 (the rear sensor, or the sensor after the converter). In fact, it would be a good idea to test each oxygen O2 sensor while you're at it.

One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.

SOURCE: 2004 mitsubishi galant service engine soon light

my galant does the same thing i was told its the 02 senors

SOURCE: Service engine soon light just turned on in my

this could be anything from a losse petrol cap, to a loose vaccuum line, or a fault with a sensor...or womething else...very hard to diagnose without the error code number...which the engine computer logs when the light comes on......you need to take the vewhilce to a mechanic, or auto-zone on the us who will read the codes for you...this will give you the directioin to which will find the answer

SOURCE: 2002 mitsubishi service engine soon light without any problems

My check engine light has been on for over a yr and a half now i have done EVERYTHING possible to fix this and spent tons of money on replacing parts that the diagnostic machine told me still nothing has worked! any other suggestions on what i should try next??