What does the check engine light mean when it illuminates and how do I reset it? This is an 05 S Type w/4.2L V8.

 

It means that there is a problem, if you get an elm 327 and use a program you will be able to read the code. That will tell you what is wrong.I use EOBD-Facile which can be used with windows or MAC. The full version also will let you reset the code.

How ever the first thing to do is check your battery because if the voltage is low you will get false codes. Change the battery over night and then turn the lights on 3 mins and then see if you have over 12.8

"So people have been replacing probably good batteries because they weren't being fully charged

In fact we've not been able to find any battery which is confirmed to not have calcium in it.

They and AGM batteries too, need 14.4 volts to fully charge.

OK... to test them for full charge, you can find what's called a "State of Charge" chart in many places on the web.

For a non-calcium (lead/antimony plates) battery, when it's fully charged it will show 12.65 volts after the "Surface Charge" is removed, or after resting for at least "several hours" - I take that to mean at least 6-8 hours, e.g. overnight. Measure before starting the engine, and directly on the battery terminals.

Calcium and AGM batteries will show 12.7+ volts when they are fully charged.

At the 13.6 volts which the 2002.5+ 2.5-litre and 3.0-litre S Types provide, they will only charge to 75-80%, 12.4 volts. " copied from Jim _S-V6_2004 ahttp://www.jaguarforum.com

 

Thank you!

 

In addition to the excellent advice from Ducmon, don't be surprised if there is more than one code. Write them down before erasing them (the actual code number, not the description) and don't be surprised if they return the next time you drive the car.

Write down the new codes but don't erase them just yet.

Let us know what you find.