2004 XJ8 - 47K miles

Had her now for 2 months and is sweet as ever. I really love the handling and nimbleness of this car which I am not ashamed to say I put to the test on a regular basis. Brings a smile to my face every time I push her a bit...

Anyway I digress... to the point of my post

I am trying my best to avoid the dealer.

The check engine light came on after -- I think --- the wife put some crappy gas in the car. Miss-fire codes

I filled her back up with premium, threw in a bottle of injector cleaner just to make me feel better as I know the odds of it making a difference is small.

She is running fine purring along with no issues. I ordered a scanner from ebay - the one you plug into your laptop-- just in case I need it again -- $20, but it has not arrived... Due in a week or so, so I'll see if I've been scammed or not

Searched the web but as usual its hard to really get to what you need to know, bottom line, I could not find anything determinate on how to reset the engine light.

Am I forced to make a trip to the dealer? Or is there a way to skip the $120 they want just to open the divers door...?

John

 

I'm puzzled how you could know you had "Miss-fire codes" if you didn't have the code reader? AFAIK, any code reader has the ability to clear the codes, which turns off the light.

But no mater - just go to any auto parts store. All the major chains like Auto Zone will read the codes for free (and clear them too).

 

I should have said that I had my trusted Autozone representative read the codes. He mentioned that he could not clear the codes. Who am I to challenge the knowledge he has accumulated over the years of reading 1000's of cars.

I'll take her back and ask nicely!!!

Thanks - my relief of avoiding the *********** visit is worth the grovel!!

 

Definitely get all the codes, diagnosing a single misfire vs multiple misfires, one bank or two...will change the direction in which you'll get advice.

 

Quick Update: Just received my OBD II Diag Interface USB scanner. (Total $21). I installed the SW on my PC (note I have an old Windows XP laptop whwre it worked. On my Win7 laptop I had some driver issues and could not install). My options for configuring were Com Port 4 at 38K baud - yours may differ. Was able to capture the codes: P0300, 301, 305, P1111, P1316..... Missfire -I will now investigate further.

Cleared my check engine light...... and for right now all is good.....

 

Oh and one other thing -- It was easy, so if you were like me -- a bit hesitant I'd say get yorself one and debunk the mystery - you never know when it may help. It tells you all sorts of things about how the car is running and is a handy tool to have. Already saved me a trip to the dealer, granted I didnt fix anything tho!!!

 

I also have a 2004 XJ8. Go to www.CanOBD2.com and you can get the definitions for those codes free. You'll find other info that will help. Select "Repair Solutions" and you can put in your car's info and can buy solutions to your problem if you can't find it elsewhere. (about $15.00)

At the auto parts or online you can get HAYNES TECHBOOK, OBD-II & ELECTRONIC ENGINE MANAGEMENT SYSTEMS. Their "part" # is 10206. It tells what the stuff is and does and how to test stuff out. It has some code def's in there; the generic's and some car brands, but not Jag.

 

They probably won't clear the codes for you at an auto parts store, because of liability reasons.

 

Buy an OBD-II reader.. best $200 you will spend, use it on any car, diagnose most issues and best of all clear whatever codes you want.

I have an Actron CP9175 works great..

 

For my DIY I got an Equus 3130. Amazon and Walmart online sell them for about $129.00 They list for $311.00. It lets you see the data as it is happening. It will show you the "Freeze Frame" info too, but when my 2004 XJ8 did the P0121 thing, the captured data showed a throttle position reading even though that was what was supposed to be the trouble. The new Equus 3040 will let you see the live data too. I have seen them for under $100

 

My $21 ODBII reader with USB PC setup also shows "as it happens" data on the PC screen. Being a cheap Scotsman the price and functionality really has me smiling.