Hi finally got my dream car ...unfortunately having issues
2001 xk8 117k miles full service history...tensioners, water pump and coolant tower upgraded
After driving perfectly for 4 weeks I got a gearbox fault issue

It went in to reduce performance and also stayed in 4th

Occasional it seems to jump gears about at low speed...like its trying to change

Also a occasionally red warning with persc. T

Battery is good and was disconnected and charged over night

Fault codes


Codes on code reader

Can anyone point me in the right direction please

 

Loads of reports on here concerning batteries Richard. Even when they seem fine they can cause loads of strange problems.
I started to get regular 'Gearbox Fault' and DSC not available messages. The car always started first time and never gave any indication of a duff battery. I changed the 4 year old Bosche for a Varta and all the problems disappeared. The Bosche is now performing perfectly on another car.
Good luck
Pete

 

+1

That's two codes telling you there's an air leak, a collection of others complaining about the transmission, and a CAN fault. Unlikely (but not impossible) they'd all appear at the same time.

Good luck,
Mike

 

Battery would really cause this and limp mode...do we have a good way to test???

 

Battery issues do indeed cause all sorts of codes to be thrown. Replacing the battery often cures things, but I believe that -- when the old battery tested good -- what really fixed things in many cases was freshening the battery connections. Just a tiny fraction of an ohm of resistance can pull the voltage down when starting the car ... codes can follow.

A "load test" is often recommended but this can in practice be many different things. A very reliable test of a battery's health is to get a handle on its "rest voltage", this gotten by fully charging it, and then letting it sit with no load overnight. Best to disconnect it from the car for this. I'm generalizing a bit, but if you see over 12.5V rest voltage it's probably good. Finding that, I would go hard at cleaning the connections, clear the codes, and see what develops.

 

The two lean codes, tell me the fuel mix is off. Could be air leak. I'd say to start with changing fuel filter, air filter, spark plugs, and the crankcase valve (disc looking thing on top of engine). And get inside the throttle body (dont take off of car) and give it a good scrubbing with a toothbrush and throttle cleaner. Get all that burned oil out of there and on the flap upside and under, and the inner walls till no more black tar. Dont change out O2 sensors, yet. As you will be told "that is the issue" Do all the above first. Plugs are VERY important, if they are bad, they'll take out a coil or 2, and that will lead to raw fuel in the catalytic converters and kill those.

 

Thank you all so much

OK did the rest test ....
13.1v b4 disconnect
12.9v after 12 hrs disconnect

Given batt terminals a nip


So whats next?

 

Clear the codes and see what happens.

Don't worry about the P1000 at the moment:- it just means that the system readiness tests are not complete since the codes were last cleared. It will remain until they are, when it should change to P1111.