Reddit mentions of iDiagnose Smallest Super Mini ELM327 V1.5 Bluetooth OBD2 OBD-II CAN-BUS Auto Diagnostic Scanner Tool Wireless OBD2 Scan Tool CAR Code Reader - ANDROID Compatible

They go cheaper without the cable.

NOTE: this is Bluetooth. It does not work with Apple Bluetooth because these are pretty much never "Apple approved" BT devices. iPhone/iPod users will need the WiFi readers. The iOS app is Horsepower, not Torque. I'm not sure about HP, but Torque Lite is free and will read codes and display engine data. Torque (paid) is what's $5.

I'd recommend OBD Auto Doctor (onboard diagnostic) for $10. Then get a cheap Bluetooth OBD adapter from Amazon. The one linked below iDiagnose ELM327 is $15.

http://www.windowsphone.com/en-us/store/app/obd-auto-doctor/68fcb70d-c259-4e1d-8158-27735854493c

http://www.amazon.com/gp/product/B00A1O72TW/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

I've used a few OBD-II interfaces, one serial, two USB, and my current fav is bluetooth. I got it off Amazon: http://www.amazon.com/gp/product/B00A1O72TW/ref=wms_ohs_product?ie=UTF8&psc=1

They all create serial devices in Windows and Linux and the bluetooth one is physically isolated from your computer so you can't do anything to power surge the car computer.

while the deal per se is good, I'd advise to purchase a device like this one instead

http://www.amazon.com/iDiagnose%C2%AE-Smallest-Bluetooth-Diagnostic-Wireless/dp/B00A1O72TW/

and install on your phone one of the apps that support them... This one comes to mind

https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en

I bought this one http://www.amazon.com/gp/product/B00A1O72TW?psc=1&redirect=true&ref_=oh_aui_search_detailpage about a year ago and its still going. Its been plugged in ever since I bought it and its smaller then some of the others so it won't get in the way.

Go out and get an OBD-II scanner. Trust me, it's a solid investment that won't set you back much at all. If anything, it's probably the best "bang for your buck" accessory you can get for your XJ. It'll let you read CEL codes, reset them, and you can use the Torque app (which is pretty cool to have for the info).

I bought this one about 3yrs ago, it set me back a whopping $15.

iDiagnose® ELM327 V1.5 Bluetooth OBD2 OBD-II CAN-BUS Auto Diagnostic Scanner Tool Wireless OBD2 Scan Tool CAR Code Reader - ANDROID Compatible