The error is P0105 -Manifold absol./barometric pressure.
It has actually been appearing every so often for a while, but on a couple of occasions last year, the AA came and cleared it.
More recently, after a replacement battery the EMC light came on again with this same error. I now have my own code reader and after looking back historically and seeing this had appeared before, cleared it. All was fine for about three days before it appeared again. So cleared again and after about the same time the error came back again.
Had the MAP sensor changed as also a damaged wire repaired, we suspect a rodent has been at work, and once again, three days later the same error returned.
So, with a new MAP sensor, the error is returning. There is also the P1000 error message but there are no other symptoms. It has been suggested there could be a problem with the EMU but really hoping not.
Ignore the P1000 code. It just means the car is ready to accept diagnosis.
I ask this because if the metal crush gasket between the base of the throttle body and the inlet manifold wasn`t changed, then you could well have an air leak. Tightening the throttle body bolts might also be worth a try.
You might also go around the inlet trunking generally and tighten jubilee clips to ensure there is nothing slightly loose there.
I`d also have a look at the connector onto the throttle body to ensure there is no corrosion on the pins. Working the plug on and off several times can often shift any corrosion and reduce current resistance on the pins.
Although I`ve previously owned a naturally aspirated 4 litre V8 S-type and know that early V8 set up well, there were changes made to the later 4.2 V8 found in the X350, later V8 S-type and also the 4.2XF and 4.2XK NA models in the inlet and throttle areas. I`m also familiar with the XJ and XK 4.2 supercharged engines but lack detailed hands on experience with the layout on the NA 4.2 units. That said, they are all much of a muchness.
Whilst you are tinkering, also check the condition of any rubber 1/8" ID bore pipes that may be connected to the inlet manifold downstream of the throttle body and also any others that may be present upstream of the throttle body. These pipes do harden, embrittle and split length wise, often where the fit onto any vac or pressure stub pipes. Replacement lengths are available via a Main Dealer or indeed off the rack at Halfords. In my opinion, the Halfords pipe is of higher quality and cheaper to boot.
It is also worth checking the tightness off the inlet manifold to the cylinder heads. Any air leak there could upset the MAP sensor. Again also check the MAP sensor plug and socket as detailed above.
It is unusual for the 4.2 NA to kick up engine issues. It really is something of a bulletproof unit so I`m surprised to hear about this issue. Issues of this nature with this engine are very rare indeed and I`ve not come across this one in over fourteen years of running V8 Jaguars. I`m therefore interested to see the eventual outcome to this problem. In the meantime, I`m happy to try to help you find a solution.
Looks like the ECU and MAP sensor are actually fine which is good news.
Seems to be running fine and so does not look like an air leak as their are no corresponding errors.
So we are back to a problem somewhere with the wiring it seems.
Looks like the wiring to the MAP senor is fine as it passed the load testing with no problems.
Same fault occurred returning tonight after not being able to duplicate the problem typically.
The in addition, got the DSC Not Available message with its own light as well as the amber warning light. There was no sign of any change in performance though. Continued to drive fine.
I am wondering if this might be a red herring though as I suspect the battery may not be as well charged as it could be. So will comtinue to test and see if there are any more clues as I go.
These electronic Jags need a premium grade battery ie Bosch or Varta to perform correctly. Cheapo, budget batteries won`t last long and their inbuilt construction and technology is often just not stable enough to keep up with these highly electronically/electrically sensitive machines.
As always, start from a known point. In the case of a Jag, that really does mean a decent battery. That done, many ills often simply disappear.
If it is a failed battery then I would say it was still under warranty but I suspect with more regular use, the battery will get back up to full power. I have a commute of around 20 miles each way so a week or so of that should have the batter back to normal.
I did do a general diagnostic and found quite a few errors. But many were form items that are not on my car such as it not being able to connect to heated seats (which mine does not have). Another one was B2325 Passenger exterior rear view mirror feedback potentiometer low. This mirror needs replacing as the autofold does not work nor does the electric adjustment which is what I would say gives this error.
So I will continue to update here. I feel it is a case of eliminating the possibilities until the root cause is found. I am sure someone else must have had similar at some point too.
After about a fortnight and over 400 miles the EML returned with the same error. Same as previously with the XJ8 driving as well as ever. No new symptoms although, probably unrelated again, the doors do not seem to automatically unlock after turning the engine off and going to open the door. I have now got into the habit of pressing the unlock button before taking the key out of the ignition. This has been happening for quite a while but is now more often than not.
The other almost certainly unrelated symptom is the lights flicker off while driving, sometimes more so when having indicated to turn. I am pretty sure this is a poor connection in the control stalk.
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