From what I read I may have error codes due to the battery being dead for a while. (Changing water pump outside, had to work with the weather) Has new battery but fuel gauge goes from 1/2 to empty and back while driving. Just filled it up and have not yet seen any movement.

Horace
2 1995 E-320's

 

Try this:

1) Turn ignition key so that you get all the warning/check lights to come on, but not far enogh that the engine wants to turn.

2) Hold the accelerator down about 5-10 seconds...all the way to the floor. The various lights should blink (and maybe go off...I forget)

3) Turn the ignition key back to off and pull the key all the way out.

4) put the key back in and fire it up.

5) let it idol for approximately 3-5 minutes to let the computer relearn the various systems and gather signals from all the sensors.

6) take it for a drive, brining the engine up to full operating temperature.

That's it. You should have no error codes or idiot lights....unless you really have an issue at which point you probably have whatever it is looked at.

 

Hmm, all I've ever had to do to clear the CEL is unplug the battery for at least 30min. But ShanMan's recommendation sounds like there's a more intentional design for this... but if that doesn't work, just try unplugging the battery for a while.