Hi guys

I recently bought a '99 XJR, 73k miles, and it appears to me to be in perfect mechanical order in that it drives beautifully. However, I know little about engines and car mechanics in general and of course I know nothing of the history of the car (beyond the carfax report!) Do you think $46 (the cheapest I found) spent on a codes scanner is a worthwhile investment ?

Am I right in thinking thatthere may be all sorts of errors on the vehicle that I am simply not aware of because I cant currently read the codes. Or would I see a "check engine" light if there were any errors ?

Any comments appreciated.
Cheers

 

Hey wdmoreton, regarding your question, it depends on if you would like to see more than just the basic engine and transmission codes that almost all code scanners can pull. I say 'almost' all, because there are some scanners that just don't like the jag interface..i know it is supposed to be read by any and all, but there are those out there that cannot connect. My '03 XK would not be accessed by Autozone's scanner, and 97xk also couldn't communicate with anohter retail unit (don't know which one though). My AutoEnginuity scanner (laptop based) works just fine, and 97's car communicated just fine with the dealers...so they are finicky.

I started a scanner thread awhile back here, and there are some brand/models that other jag owners have found to be successful in at least communicating. Could be something closer to what you were looking for.

Now, on the number of codes that can be read, there are the basics (required by law) such as the engine and tranny, then there are about a bazillion (ok, not that many...but alot) of other modules, sensors, and gizmos that are not required by law to be read by the basic OBD-II protocols...often referred to as 'enhanced codes', such as ABS, air-bags, and cool stuff like seat/headrest electronics. The AutoEnginuity scanner was the cheapest one out there that could both the basic and the enhanced features...roughly $500.

Lots to chew on, but really depends on what you want to see yourself...or agree with yourself to pay the dealer $125 each time you want a diagnostic ran on your car for those 'buried' codes.

As for a 'check engine' light, or other message indicator lights, some codes cause the light to remain on, other's do not. While it may not remain illuminated, say it triggered it temporarily, often the code remains in the computer so that it will be there when teh scanner is attached, and will remain in the system until you can 'clear' it. This allows you or a tech to do preventative maintenance on an issue before it can cause catastrophic failure later...such as a wheel speed sensor going bad and killing the ABS system...perhaps when you really need it.

BTW, the autoenginuity allows you to clear all codes, most cheap scanners can't even clear the basic 'check engine' light.

 

Thanks h20boy, thats a very comprehensive answer! You have answered my question i.e. the basic scanner is probably not much use even though it is cheap. I dont want to spend hundreds, so for the moment I will rely on the dealer if I get warning lights.

Thanks for your time, you greatly increased my understand of this subject.

 

Glad I could help! i was where you are once, and eventually owning a code scanner became a more convenient option. If you're not getting multiple codes or only once in a blue moon, dealer oversight is probably the best answer. Having your own comes in handy if you are doing repairs yourself, and want to see if your fix actually worked, clear the code, try the car, and see if it returns. You can see how it wouldn't be fun going to the dealer each time you try to fix air leaks, 02 sensors, etc.