I am a new member here with a 2003 S-Type 4.2. Yesterday, I serviced my Jag with 102k miles on it (I just bought this car last week and the previous owner had a Jag dealer perform all maintenance schedules except for the 90k and the 100k). Anyway, the car was running perfectly and I just did a oil and filter change using 5-30, changed a very dirty air filter, cabin air filter and spark plug change using NGK Iridiums set to .037. Took car for test ride of approx. 10 miles and ran great. Today, after traveling about 5 miles, the "check engine" light came on and the display intermittently now reads "performance restriction". Car still seems to be running fine but I pulled into a repair shop and had him plug in for the codes and it read P1171 and P1174 lean on both banks. I came home and took cover off looking / listening for air leaks and have found nothing. Does anyone have any ideas of what or where problem may be?

 

Vac leak, most likley due to pulling off the airbox. At least that is where I would start.

 

Very good advice!! It's a battle to get the air box open and resealed properly without breaking something.

I would add a tip I use on my 2005 STR and my wife’s 2003 Lincoln LS. When I get into the air box to change or check the filter. I always remove the entire assembly from the car. Undo the hose clamp on the intake, unplug the MAF, remove PCV hose and the one bolt holding the air box down, remove the small plastic screw holding the fresh air intake down. If you have the STR don't forget to unhook the air flapper electrical plug on the side of the air box too.

That way I can clean things up much better. Plus I can finally get a good look at the pulleys and belts.

Do you change the serpentine belt? It’s time if not. Also change the fuel filter. It's hidden pretty good and no one changes them.
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You mean P0171 / P0174 ???

 

Thanks everybody. I will go pull the air box now and try that. QUESTION - If the airbox fix works, will the check engine light turn itself off, or does dealer have to do it?

Yes, I have a new fuel filter to install but I have not gotten to it yet. I watched video on here about fuel filter and it looks pretty straight-forward, just a PIA to access.

I did also see that serpentine belt change was part of the 100k service and still need to buy one and do that job. Was hoping to find a Haynes manual to help walk me through some of these things but looks like they didn't print one for this car. The serpentine job looks involved and plain nasty.

Jag8 - Working off of memory, pretty sure the shop said code P1171 and P1174 - I know he then said left and right banks lean. Only had this car a week, so I will have to get a code scanner (currently researching that too) .

Thanks for all the help.

 

They'll be P0... not P1... which have different meanings entirely and I'm not sure those ones exist for your car!

 

Well your in luck because we have the JTIS and the JEPC on here for free. The JTIS is the service manual and the JEPC is the electronic parts catalog.

Take the time to install them. Worth it.
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Yes install JTIS and JPEC. I bought a pdf manual on eBay but the one you can download for free is much better. I purchased a Chinese Bluetooth OBD adapter on eBay for about $16 and downloaded Torque app for my phone to read and clear codes on my car. Works pretty good for only $25.

 

Thanks for manual info, I will search forum for them now and download. All these acronyms....feel like I am back in high school Latin class (wasn't pretty). I saw there was a cheat sheet for them somewhere, think I will need to print that out.

I redid the air box as per earlier posters instruction, but it didn't rid the check engine light illumination (I was just in garage haven't taken for drive yet). Don't know if same codes are showing though or if a reset is necessary or if light goes out on its own.

Great helpful group on here though. I appreciate crash course education I am receiving.

 

It can't see a fix till you drive it from cold 3 times or clear the codes and at least 2 times.

 

Thanks (again)Jag8. You means driving it 3 or 2 separate occassions fom cold start? Canyou direct me on clearing the codes? I dont yet ave a OMB scanner.

 

Yes, from cold. Just get one they're sooo cheap!

 

I used an ELM bluetooth and Torque for Android. Works great on clearing codes and seeing info when you drive.

 

I use the same that Michael is, works great.

 

Thanks all. I stopped at Auto Zone today and had them reread diagnostic code. I had reinstalled the air filer per Tbird66 and also tried the trick of spraying either at different breather / seal points to see if engine revs - it didn't. Anyway, I also did the 3 drives from cold start as per Jag8 suggested to initiate a CEL reset to no avail. Car ran fine all day, CEL stayed on but it never read 'restricted performance' today. The Auto Zone store this afternoon read fault codes - P0171, P0174 and P1111. After leaving Auto Zone I made 2 stops and approximately 15 miles later, the CEL turned off. That was now 40 miles and another 2 stops ago. I am unclear on code P1111 as I read both that it ment O2 sensor or leak and also an all clear / good condition status. Wish I was smarter with stuff. Have ordered a diagnostic scanner OMDCOM. In the end, what do you all think may have happened? Thanks.

 

Sounds like you got it finally!!

Don't worry as the P1111 should be present if all the readiness monitors are set. This is needed when the car is emissions tested.

I would get the codes read one more time and cleared just as a check.
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Will do. I'll try to wait for scanner to arrive and read again since Auto Zone can't clear codes. Hoping the scanner tool is going to be straightforward in how to use.

 

I think if you slip him a couple of bucks he'll clear the code for you.

 

Well I know they can but some of the dummies working there don't know how!

Next time just look at his code reader and show him the clear codes function. They use one of the same models they sell. I have had them tell me the same thing until I showed him. Once in a while I get "it's against the law".
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Gah now mine is throwing the same codes Time to track down a vac leak....