"Restricted Performance" Causes?

[Force4145]

Hi All,

Does anyone know what the most common causes for the "Restricted Performance" warning are?

Thanks

[JOE-DOT-COM]

HI

Could be one of many, many faults and any advice will be pure guess work and will cost you a fortune in replacements parts you dont need

you need to get it plugged in and read the faults codes to send you in the right direction

but a low battery will cause many issues on the s-type and a lot will cause restrictive performance

put the battery on charge over night and see if it cures it, may only cure it short term if battery old

cheers

Joe

[Mark Five]

I agree with Joe re: the battery - I had bad problems with the 'gearbox fault' message until I replaced the battery, which cured the problem.

[Force4145]

Thanks. I'll check the battery voltage first thing in the morning when the car is cold. Cheers, Nick

[Force4145]

I checked the battery this morning from cold and got a reading of 11.91volt. Does that seem a bit low? The battery is a Yuasa HSB019 and is only a year old. It has a 5-year warranty.

[Old Peter]

Hi Nick,

That does seem too low.  I think 14 volts should be nearer.

Do you charge the battery regularly or have longer drives to keep the battery fully charged.

If so, the battery should be changed under the warranty.

Regards,

Peter.

[clive 2003 S-Type]

I also had a restricted performance warning light for over a year.  I went to Jaguar dealer 3 separate times, spent over $450 and they could not find what was wrong with it.  After reading some posts on this forum last year, checked my battery and it had low voltage.  I bought a new battery and BINGO, never had another problem with the restricted performance warning light, since last February, when I installed the new battery.

[JOE-DOT-COM]

hi

if thats 11.9 with engine off, yes thats too low, that would drop to about 10v I bet once the engine cranking

put it on charge overnight and see how it goes, if it drops again, will be new battery

if your cars a diesel, that will  causes you lots of faults once the pre heater kick in on start up

did you check it on start up, should be over 14.5 volts

cheers

Joe

[Force4145]

Hi Joe,

I just tested the battery voltage on start up and I got a decent reading of 14.7 volts. So, perhaps it's not the battery after all?

[Force4145]

Been to the garage and they said it could be the Mass Air Flow Sensor. They had one in stock and tried it alternately on each side (there are two) but the warning kept coming up. They want to try changing both sensors for new ones. Do you think that will help?

BTW I read that if you disconnect the wiring loom connector with the engine running, the engine should cut out if the sensor is working correctly. I tried it on mine and the engine stayed running, implying that one or both sensors are faulty. Does that sound correct?

[Ugo]

12v automotive battery condition from voltage measurement:

Voltage.     state of charge

12.5.             90%

12.2               60%

11.9               40%

11.58            20%

Battery should not have been charged or used for about 1 hour before this test