2003 Jaguar S Type R 4.2L SC. Check engine light on with rough idle and computer statement stating that performance is restricted, engine will not exceed 2500 rpm? Any Hints?

Your description indicates the engine/coolant thermostat is faulty and allowing at least some coolant to continue circulating so at higher road speeds the engine is over cooled.

You have a fault condition in the the engine management system - get the codes read to indicate where the fault lies ... It is probably just a faulty sensor as this is the most common cause of check engine warnings. The restricted performance condition is meant to protect the engine or components from damage, so don't panic - get the codes read - its probably not as bad as you expect. hope this helps - good luck.

This is a 'limp home' safety device. For example If you ECU gets a signal from a knock sensor due to a miss-fire the ECU will restrict engine performance to prevent any lasting damage until the causative error as been corrected. Do a good visual check. Check plugs, leads, disconnect sensor plugs and reconnect them. If automatic ensure that your transmission fluid is at the correct level. You can top it up one pint at time via the transmission fluid dip stick tube. Always check the levels with engine running in 'park'. If there is still restriction you will need the on board diagnostic report to read from the ECU. This will give you vital clues as to the cause of the 'restricted performance' measures being imposed.

First step is to drive to AutoZone or Advance Auto Parts carefully, without heavy acceleration. Tell them you have a check engine light and you need the computer scanned. They'll do it free (a dealer will charge an hour's labor even though it only takes a few minutes). Ask them to give you a printout of the codes, and post them here. Do that as a reply to my post and I can help you decipher the codes as to what they mean and what needs to be done. Was the car sitting in water deep enough to touch the bodywork, or were just the tires touching water?

I had the same problem. Restricted performance and running rough at 3000 RPM. I have an OBDII code reader and found that the problem was in the air mass flow sensor, which is just after the air filter. I pulled this out and found it was dirty and had butterfly wings in it. The last shop where I had the oil changed replaced the filter for me but put in the wrong size. Close but no cigar. Bought some *** Flow Sensor cleaner at auto store and fixed the problem. Get an OBDII reader with the ability to erase the codes. Comes in real handy.

Anything can cause the check engine light to go on from a loose gas cap, to a transmission issue. When the onboard computer detects an issue, it will restrict performance so as to not damage the engine any further. An Oil change won't affect this light. The only way to determine the cause of the light is to have the computer scanned with an OBD-II tool (Autozone does this for free) to determine the codes and cause for the light. You can also clear the light with the OBD-II tool, but if the problem is still there, the light will just come back on

you would need fault codes

o2 sensors often cause a rough idle at stand still. Previously my xj8 had crank case ventilation (pvc valve essentially) issues that caused the check engine w/ restricted performance. I noticed a severe drop in gas mileage as well. Jaguar dealer fixed my problems in a few hours and it was surprisingly cheap. Its worth taking it to advanced or auto zone to see what the computer says. Then decide if you want to shell out for a dealer fix or if you can tackle it yourself. BTW, just to justify myself this is my third jaguar. I have a '94 xj6 with a chevy 350 inside it, previously owned a 95 XJ6 and currently have the xj8. They are wonderful cars if you can put up with their rough times.

I own an '01 S-Type and have had to many problems to list, however 3 months ago mine started riding rough, the check engine light actually started blinking and it shook pretty bad especially at stop lights (although it didn't shut off) I drove it straight to the shop and they said it was a bad ignition coil (coil #4) - $135 total and it ran fine. 2 months later coil #5 went. I was advised that if you take it to the dealer they will replace all 6 ignition coils at once charging you over $1,000. They are only about $60 a part stores. Good Luck I'm getting rid of my Jag this week! What a pain in the neck beauty!

My mechanic said that the front cxygen sensors needed to be replaced on my 03.