I'm getting a P2601 code (Aux pump performance) and going into restricted performance after about 2 hours of driving. This seems to severely curtail acceleration at high speed but the car is still quite drivable.

I reset the code but it comes back after the same amount of time. So do I need a in inter-cooler coolant pump? If so, what's the real name of this thing? Or, better yet, the part number. I've seen a couple of different pumps on the internet and I'm not sure which I need.

BTW - 2006 XJR

Thanks

 

Would that be the pump hidden behind the RHS front bumper? It is electrically driven, I believe it should only come on for a short time if you turn off the engine when it is very hot, to keep circulating water and prevent hot spots.

Have not had any trouble with mine so no practical experience of it, TG

I wonder if your main water pump is OK? The temperature gauge on the dash is not very accurate.

 

I believe the main pump is good I've got no other codes nor a CEL and no other problems. I checked the fuses on the right side of engine bay, I think that's where the fuse is for the pump and none blown.

As mentioned, when I clear the code the car runs great. It takes about an hour 15 to get to work. On the way home, just about the same place, the car goes restricted so I'm guessing there's a set mileage before the code gets thrown. So either the pump never works and the computer waits a set value before it faults or, as you said, it only comes on when needed and it fails then.

Either way I figure I should replace it. Anyone got experience doing this on an x350? Should I go with a Bosch?

 

I would be tempted to take off the hoses first and look for any delamination or other obstruction. A replacement pump will be rather costly.

I think I have heard of a problem in a hose on the main pump, possibly where it has a junction. You may find it mentioned on here or on the UK forum.

Does the temperature gauge show a bit high before the fault occurs?