2004 XJ8 131k miles.

80% of the time suspension works normal. Intermittently after the car sits all night, when you "wake up" the vehicle it purges all the air out of the front suspension with the loud hiss noise and I can imagine it is releasing all the air out of res. After 1-10 key cycles the compressor will fill the front suspension and every thing will go back to normal.

Question is:
What is telling the car to release the air upon wake up, front level sensor failing? Suspension control module failing?

What we know:
All struts are holding pressure.
Compressor works.

My Jag scanner is down so I can't do as much as I wish I could.

 

I've moved your post from the general tech section to the XJ (X350/X358) section for better visibility/response from techs/members more familiar with your model


regards,
steve

 

Does the suspension collapse or is there just an exhaust of air.

 

Every once in awhile when you wake the car up from sleep mode it purges all the air out of the front suspension, with in a few minutes only the front suspension is completely deflated.

From what I understand when you take the vehicle out of sleep mode via key fob unlocking or door opening the suspension will start leveling in antisipation of people sitting in the car or other heavy items being placed in the car. I'm guessing the front suspension level sensor is giving off reading that the car is to high or the control module is malfunctioning and releasing all air out of the front suspension.

 

I agree it looks like a duff height sensor if you get no fault codes, but does the car come back up after engine start ?

 

The compressor runs every time I cycle the key .Some times 1 key cycle will fill the front suspension, some times it takes more than 1 key cycle. I'm guessing it doesn't fill until the sensor tells it to.

Has any one installed this sensor with out calibration? I'm wondering if this replacement can be done with out the jag scanner.

 

front ride height sensor ordered part # C2C40510. Looks like the sensor comes with all the hardware so I'm assuming theres no need for calibrating since I don't see an adjustment.

 

Your assumption is not correct as I understand it. The new sensor has to be set with the Jaguar diagnostic software using a PC or laptop. The new sensor is fitted, then the system is used to set the ride height and thus recalibrate the system with the new sensor.

 

Fraser is 100% correct.