Hi Everyone,

I will make a very long story as brief as possible, I drive a 2006 XJR.

As of two weeks ago, I had a check engine light and an air suspension fault light pop up. I had a ride height sensor changed in addition to the evap. canister sensor changed and it seemed to have resolved the problem.

3 days later, the 2 lights returned indicating the same problem I went to my mechanic and had the codes cleared, and it was okay for the remained of the day. Later that evening, I took the car out to get some gas and the 2 lights returned once more, I filled up with gas (same gas station I always go to) and returned home.

The next day (yesterday) the car was dead, it would crank and crank but would not turn on. So I had to have it towed to my mechanic, of course the minute it was taken off the tow truck it starts right up and all the codes are gone. WTF! I had him scan the ECU again and 756! Yes! 756 fault codes came up and the front end dumped into the wheels.

Frustrated I left and went to work in my very reliable Audi A4. My mechanic called me and said it looks like their appears to be a fault with the ECU. I said okay whats a new one cost? He says: $2600 bucks. Are you kidding me? After I just spent $14,500, 6 months ago replacing 2 headlight ballasts, 2 fuel pumps and a heater core!

Frustrated, I told him to hold off on doing anything and I will think about it. So what are my options?
Do I get a new ECU?
Does this sound like an ECU issue?
Is there another underlying problem?
Are there ECU repair options?

I will be getting a second opinion from the dealership but I do need help.

Thank you for reading.

no sounds more like a battery failure than ecu. I would have the battery tested using a testor that tests voltage as well as cranking amps. that many codes usually says poor power and or grounds. A jaguar dealer will have a genrad testor that does these as Jaguar corp is very definative about using this testor when testing Batteries in Jags for proper capacity. Past that I would clear all codes and start again to see what comes up. If the CAN network went down it too will through lots of U codes and you can have a no start with crank based upon what leg is affected.

Thank you for the recommendation, apparently there was a bad ground and that was resolved with ease.

Now the new issue is every time you step on the gas the "Air Suspension Fault" light comes on and when your brake the "Vehicle Too Low" warning comes on.

When you don't have your foot on the gas pedal there are no warning lights at all.
Any idea what could be causing this?

Agreed, these cars are very sensitive to voltage/amperage & bad grounds.

Is the vehicle too low? If not, I would suspect a faulty sensor or re-calibration required.

No the vehicle is not too low, it simply states that there is a fault code and it is too low.

I think you just have to work through the fault codes and take relevant action. "Vehicle too low" would seem to be a height sensor problem if the vehicle seems at its normal height. I think your 2006 has one at the front and two at the rear.

The air compressor is also a perennial fault item and can also bring up "Suspension Fault", especially in cold conditions if it is getting worn out. The compressor does not suddenly fail, it just gets less and less efficient, so it times out before the correct pressure is achieved in the reservoir.

Have you replaced the compressor in the recent past ?

I spoke to my mechanic this afternoon, all the sensors were replaced and all the lines were checked.

We are going to try and replacing the control module and see if that resolves the problem. I will keep you all posted.

If your tech does not have the Jag dealer computer, he cannot reset the sensor levels, you may need to get it to a dealer.

Correct, only IDS will allow re-cal, which is why I asked if it had been done.