Check Engine Light

First, I would have the check engine diagnostic codes read to determine if they're related to the fluctuating gas gauge (not likely).

The gas gauge 'sending unit' is part of the fuel pump assembly *inside* the gas tank - if it's bad, you'll be having to drop the tank.

See "Related Questions" below for more

Trouble code P0101 means:Mass or volume circuit range performance problem

When you are ready to start the engine, just turn the key to the first position. This will display all the icons in the 'gauge' area of the dash. The engine icon is located lower left. Go ahead and complete the engine start. If the engine icon disappears, that is 'normal'. This icon can be triggered by conditions other than those on the 'INFO' system check display on the console.

If the engine icon appears while running you will need to find a service facility that can read and interpret the stored code(s) that caused the warning condition. With this information you can at least start to narrow your search for a maintenance solution.

Check for a blown fuse. have checked fuses with meter under driver side dash and under hood on 2004 explorer

Under the hood, remove the fuse panel box. Remove the B fuse for 5 minutes and put it back in.

An ignition misfire has been detected

lean means not getting enough fuel. 1st change fuel filter. (Clogged filter-no gas)

Then run car. If no change, check pump pressure @ passenger side injector rail Gage Fitting. (looks like tire valve stem) Had same problem - was dirty filter - hope it is for you. Good Luck

An engine misfire has been detected

check engine light codes can be checked at a local advanced auto or auto parts store. it needs to be hooked to a diag machine. if you're looking for the plug, it -should- be under the lip before your pedals, beneath the steering wheel.

The engine power reduced light will turn on in Chevrolet HHR when a failure is detected in one of the sensors or engine components. An OBD II code reader can determine the cause and help with making repairs.

Goto autozone or advanced auto. The plug is under the drivers side dash right above the pedals. They will even give you a print out at advanced auto parts store.

check to make sure both the gas and oil cap are straight and tightened. Fill the gas tank if you find the gas cap was loose to build up pressure and that usually resets the check engine light to off. http://wiki.answers.com/Q/How_do_you_turn_off_the_Oxygen_sensor_light_and_the_check_engine_light&updated=1&waNoAnsSet=2

It should...

Sometimes they go BANG and some times they begin to leak very slowly.

Trouble code P0404 means:Exhaust gas recirculation circuit range/performance

many cars have multiple O2 sensors. If you expected the light to go out, just from changing the sensor it won't .

Are you sure You changed the right sensor

The light may need to be re-set by a garage or using a scan tool.

What kind of vehicle are we guessing on?

Nothing catstrophic. Some of your fuel will evaporate instead of being used.

Dirty jets in the carb or dirty fuel line or faulty spark (plug or distributor)...

Trouble code P0442 means: Evaporative Emission System Leak Detected (small leak)

You don't, the light has to be repaired.

P1463 Heated Catalyst Battery Temperature Sensor 1 Electrical (BMW) P1463 ACP Sensor Insufficent Pressure Change (Ford)

For any new truck you may have to have the computer reset you can find one at Wal mart for 98$ plus tax or order on off the web. It reads what the truck problems are .

If the check engine light code is "Random Multiple Misfirings", you need a tune up. Have the spark plugs and wires changed. The loss of power is due to misfirings.

Trouble code P0430 means:Catalyst system efficiency below threshold

If it's on you need a code reader to plug into diagnostic port which will help pinpoint the problem as it could be a multitude of different things.