Oh, sorry for any confusion. I didn't mean you shouldn't touch the sensors or change the plugs. I was only suggesting you wait a little bit after one repair (new battery) and drive the car as much as possible in the meantime. A few days is okay, a couple of weeks is even better. That way if a new fault appears, the timeline should provide a clue if it was caused by something recently accomplished.

 

Perhaps a read of "Battery 101 for S-Type Owners" in the FAQ Sticky here, is in order. Compiled by many of those posting here on this thread, and garnered from experiences over many, many years as well as far too numerous threads and posts here, it really does offer worthwhile advice . . . except for one thing, that is now even better understood . . .

• it is not the dying, flat or near-dead battery that causes this thoroughly predictable sequence of FALSE FAULTS and possible codes;
• it is using the dying, flat or near-dead battery to start the car, often successfully, but with a resulting sag in battery voltage that numerous ECMs around the car will immediately report failure.

It is true that there is no empirical proof that 12.6V is a proven threshold. CCA, ambient temp, a bloke called Murphy and his Law, and numerous other factors like how urgently you need to get to the airport are also inevitable factors!

We assembled and presented it for the S-Type on the basis of analyzing many hundreds of member posts by charting measured standing battery voltage at which false symptoms appear and/or disappear. The outcome of 12.6V appears to show the S-Type is far more sensitive than other even contemporary Jags, to this "tight" headroom between what will "start" the car and what is required to correctly "run" the car.

I applaud advice, again repeated by our gurus here, to focus on this issue first and fully. Do not tinker elsewhere until you can confidently report (hand on heart and dagger to breast) that your battery voltage measures as required. Y'see . . . along with frustration, we have all seen the awe and wonderment that transforms one who watches all those expensive sounding "faults" evaporate before their eyes.

Cheers and best wishes,

Ken

 

So it's time for an update. Since my last post I've charged the battery and I still have my fault codes. Which is left rear speed sensor.

I removed the sensor and cleaned it thoroughly. And yet no success. So now i have ordered a new one, so lets hope that it solves it. I have one question about the sensor, is it an inductive sensor? If so I should be able to measure the resistance in the coil and compare it with the other 3. I have already ordered a new one but if it happens again it would be nice to have a reference.

Other than that I changed the spark plugs. And I'm happy that i did. 6/8 cylinders had a gap of 1.3mm instead of 1.0mm.

Again thanks for all the help and input. Its worth alot for a Jaguar rookie like myself.

 

Did the DSC message clear with the new battery? Sounds like the check engine light was a hard fault from the worn spark plugs, and the ABS light was another hard fault due to a bad wheel speed sensor. But if the new battery fixed the DSC message, that's another battery replacement success story.

Re: The wheel speed sensors. No experience with this particular application, but believe it is an inductive pickup like you are thinking. I've dealt with lots of other inductive sensors and despite how simple they are internally, the resistance test is inconclusive at best. If the ohm value is out of specs, yep, that's a bad sensor. But I've had plenty that tested fine with an ohmmeter, yet the system kept faulting a supposedly good sensor until it was replaced.

If easy to swap with another position, you could always try that for free. I just don't want to see you misled by a bad sensor that appeared to test good with an ohmmeter.

 

+1 . . . good post Karl.

Cheers,

Ken