I have a 2003 S-type Jag that has 60k miles. I love this car. I have restricted performance light and engine light going on. I had it in for service to fix this and my mechanic said he replaced the intake manifold gaskets. He said he used the smoke machine to look for air leaks and found nothing. I have it back now and the light came back on. I used my scanner and it says PO171 P 01/03, PO174 P 02/03 and P1000 P 03/03. I really don't know anything but purchased the scanner to be able to turn off the "idiot light". My problem is that I could always depend on the car to go when I needed it but today it did a kind of hesitation thing... from reading here and calling Jag I understand real restricted performance means the car will not drive faster than 20 mph. Any help out there? My husband wants to get rid of the car, says it is old. I don't want to get rid of it. Thanks.
PS I have tried to post on the newbie board to no avail.

 

The lights are not 'stupid' - they're telling you that there's something, potentially significant, wrong with the engine. Turning the light off with a code reader does not fix the problem, just masks it temporarily. Your mechanic either missed the root problem or made it worse.

The codes you've posted are mentioned dozens of times on this forum if you search- you might want to start by telling us which engine your car has.

 

V8, 4.2L Engine. Mechanic went over the entire car. Everything I saw on this site I asked if he checked and he did. From number 3 coil, airflow meter sensor, o ring on dipstick, air tube to throttle, breather value, air filter. Next question - if I bring it to Jaguar dealer, does the computer they have give specific diagnosis or is it just the same codes my mechanic gets?

 

Your mechanic must be short of knowledge. Take the car to someone who knows S-Types and the 4.2 engine.

If this has been happening unfixed for a while you may have ruined the cats

 

Lesson #1.. Restricted Performance is just that... You aren't able to exercise the full potential of the drivetrain. Mellow driving will be fine.

The limiting restriction you are think of is called "limp home mode" or just "limp mode". This basically is a fail safe when the computer senses a catastrophic failure but will keep the engine at idle so you still have use of the brakes and steering.

Lesson #2... Codes do not tell you what is wrong. They tell you what sensors are reading that is wrong... IE, in a recent thread, miss-fires were the codes presented but the actual failure was the catalytic converter. The readings from sensors had the computer think it was miss-firing when actually the sensors were getting out of range readings because the converter was bad..

So, like Jag V8 stated, get a mechanic that knows these cars...

And please the light is there to tell you that there is something really wrong, not an "idiot" light..... geesh