Question about 1999 Jaguar XJ

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We have a xj8 99 and restricted performance light comes on only when car gets warm. We changed the computer but still have the problem check eng. Light is on to. Any ideas

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Trisha, you won't always cause damage to your car if you have a check engine light. Sometimes it is all about some subtle pollution problem. Just to give you an example, if your transmission isn't shifting at the right time due to leaky hydraulic valves, your engine pollution standards will not meet spec and you will see a check light. There are many of these types of problems which don't easily reveal themselves unless you read the codes, so you probably won't have much luck trying to second-guess them. Also, if you vehicle goes into a "safe" mode, you will probably know it, because the vehicle will usually exhibit noticeably poor performance. You won't need a light to tell you! In this case, you should have it serviced right away.

Posted on Dec 08, 2016

Testimonial: "I just don't have the money rite now too bring it that's why I'm asking for help on here. It goes into restricted performance when it gets warm I didn't know if you would have any ideas someone told me mass air flow. When I put it on the computer I can't remember code but it was misfire in coil 4 which I changed coil 4 and it wasn't that"


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Run the fault codes as the engine light is warning you of potentially expensive problems if you continue to ignore the warning
The ECM puts the car in limp mode to help protect the engine and transmission form damage but if you continue to play at fixing rather than going to a specialist shop and have the codes read to really fix the fault it will cost you big money

Posted on Dec 07, 2016


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I have a 99 jaguar xj8 van den plaus edition. It says resdtricted performance when it Gets warm and check eng. Light stays on. I replaced the computer any ideas

For the money you spent on another computer, you could have brought your car to a qualified mechanic and had the problem correctly diagnosed and repaired. 'Restricted performance' meant the computer saw something wrong in the engine, and restricted the performance to keep from destroying the engine. You killed the messenger and still have the same problem.

Dec 07, 2016 | 1999 Jaguar XJ

1 Answer

98 jaguar xj8l p0116 p0125 codes

P0116 Engine Coolant Temperature Circuit Range/Performance Problem

P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control; ECT Excessive Time to Closed Loop Fuel Control

Feb 18, 2013 | 1998 Jaguar XJ8L

4 Answers

My 2001 XJ8L has had the amber "check engine"

Have you tried to get any codes off the check engine light?

Mar 06, 2011 | 2001 Jaguar XJ8

1 Answer

P0128 thermostat range performance is the diagnosis when diagonstic check is done. The check eng. light goes off when battery is disconnected but comes on again after a few days. Pls. advise solution....

P0128 indicates that the car doesn't "think" it is warming up quickly enough. So either it really isn't getting warm enough, or the sensor indicating the temperature is bad. If it isn't getting warm enough the causes include a thermostat stuck open, low coolant, and a cooling fan that is running when it shouldn't be.

For a good explanation and more insight visit

Keep in mind that many cars have two coolant temp sensors. One for the computer, and one for the temp gauge. Make sure you are working with the correct one.

Feb 08, 2010 | 2002 Honda Accord

1 Answer

The restricted performance light keeps coming on usually when the engine gets warm ? this is a jaguar xj8 3.2 sport 1998 model

could be numerous causes, it is logging a code when the light comes on, have the codes pulled to direct you in the correct repair

Jan 17, 2010 | 2001 Jaguar XJ8

1 Answer

Does not blow hot air

1st off check your (cold) radiator (not the overflow tank) make sure it's
full, next locate heater hoses at firewall with eng. warmed up hold both
hoses 1hose should be hot going into the the other just a little cooler
coming out when it's working right but if 1 hose is hot and the return
is just warm you may have a restriction possibly plugged heater core
now if both hoses are warm not hot it could be thermostat is not closing
properly there is also the heater ctrl. valve but i don't know if you have
a mechanical- electric or vacum operated valve.
ps do these tests with eng at operating temp. fan on med. temp set on
hot. any other ? gimme a shout good luck

Jan 13, 2010 | 2000 Jeep Cherokee

5 Answers

Jaguar s-type restricted performance

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.

Oct 20, 2009 | 2003 Jaguar S-Type

1 Answer

Check engine light is on,display says restricted performance

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

Sep 16, 2009 | 2003 Jaguar S-Type

1 Answer

Toyota Camry 2004 P0420

well that's if I'm not mistaken, catalyst system efficiency THRESHOLD!!! it is "bank" when your description code explanes bank 1 that is a O 2 sensor anything says BANK is a Oxygen sensor = O 2 sensor.what is it doing shutting off when eng warms up or sputtering or nothing really out of normal behavior? these switches will loose all communication with computer or get stuck in 1 of three ranges each range behave differently! in each range the deal with these are these switches are a part of maintenance usa @ hundred thousand km they should be change for emission efficiency and fuel consumption and vehicle performance usually after 1 is changed 9 times out of 10 shortly after the next bank will produce eng light and so on!! I usually change both while I'm at it you know pay me now or pay me again later but twice as much! well hope this helps you out good luck cheers happy new year.John, Toronto,Ontario

Jan 03, 2009 | 2003 Toyota Corolla

1 Answer


The plug is located at the bottom of the steering column.The fault seems to be the mass air meter though.

Nov 26, 2008 | 1994 Volkswagen Golf

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