Traction/Stability Control Fail


Well’s it doing it again. And before I tell my husband, so he can procrastinate 6 months, the “allow” me to take my '99 Jag Vanden Plas to the dealership, I’d like to confirm or thwart my own suspicions.

About 2 years ago when the writing was on the wall for gas prices, I stepped down 2 levels from premium to the regular and started buying wherever was cheapest: grocers, 7-11, heck the pet shop if they had it.

Some months later, the Traction/Stability Control Fail and Check Engine lights came on. At first, intermittently, then within a couple more months (yeah, I know), they just stayed on. Also, the car seemed to be getting poorer mileage and driving rougher (I could feel every bump in the road compared to the incredibly smooth ride before and I hear this rattle sound when I accelerate.)

Hubby cleaned the air-something-or other (instead of buying a new one), that didn’t work. Paid for the dealership to tell me the fuel injectors need cleaning and a belt was worn. Dealer cleaned injectors, but hubby insisted he’d bought a belt 2 years ago which he’d replace himself someday once he finds it in our overstuffed garage. (Isn’t that belt rotted now too?)

Anyhoo, yesterday the lights came on for about 10 minutes until I parked it, but not since. I still hear the faint rattling sound (almost like gurgling) and I just know it’s coming back full force.

Do you think I caused this by using cheap (less detergent) gas? And can switching give me back my smooth (and silent) ride again, while dousing the lights too? What could the problem be?


The fuel is very unlikely to be the problem. The government mandates sufficient additives to take care of that stuff 95% of the time.

I have four suggestions:

  1. That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here. It likely will have a format like P1234.

  2. Do any maintenance that is past due, including replacing, not “cleaning” the air filter. They do not clean well. A clogged air filter (that may look clean) may cost you more in fuel than a new filter. The maintenance schedule should be in your owner’s handbook.

  3. Don’t neglect those CELs. Putting that off can prove very expensive and could be a safety issue.

  4. While you have that owner’s manual out, check out what it says about octane requirements. If it says the car requires high octane, then use nothing but. Using lower octane gas can cause damage to your car and will reduce the power and likely also the mileage so there are not likely going to be any real savings, maybe some real cost however.

If it says you should use high test but may use lower octane, then using lower octane will not harm the engine, but the mileage part may still apply and you may not save anything because you may be getting less miles per gallon. 

 Note: High octane gas does not, by nature have more cleaners than regular.  It only means it has higher octane and that is a totally different measure.  It also does not mean the fuel has more energy.   It means the fuel burns slower.  Yea, that's right high octane burns slower. High performance engines often are often designed in a way that needs to have the fuel burn slower (actually harder to get started burning).


Whether “off brand” gas may or may not have sufficient detergent is hard to say, but since you stated that you went from premium to regular gas and that you began hearing “rattling noises” when you accelerated, it is clear to me that you have been operating your car on gas that is of too low an octane.

And, if you have been doing this for an extended period of time, it is very possible that you have caused internal damage to the engine–specifically to the valves and possibly the pistons. In any car this type of damage would be expensive to fix, but in a Jaguar…I wouldn’t even want to guess as to how much this might potentially cost you.

The check engine light is alerting you to a problem, and just as with medical conditions in people and in animals, delaying remediation of the problem only tends to lead to more damage and to more expense. So, I suggest that you have this car checked out a.s.a.p., no matter what your “thrifty” husband might think. If you are very lucky, you might just need new spark plugs. If you are not lucky…? And, if you plan to continue to own this car, I would strongly suggest that you operate it on premium gas, as it was designed for.

Also, the next time that you buy a car, I would suggest that you purchase one that only requires regular gas–unlike a Jaguar.


Thanks to both of you. I will follow your advice and let you know the outcome. Cheers!