Upon cold start up this morning I noticed a red light on, on top of the temp gauge. After checking I see the car threw a code of U0426. The coolant level was up to the Max mark in the recovery bottle. After driving 3 miles the gauge never got off the cold mark, I pulled over and checked, everything seemed normal so I turned around and drove home. The gauge never moved off cold and the engine seemed to running normal and not over heating.


Anyone have any ideas?

 

Hi Clamdigger,

I don't find the generic code U0426 defined in the X350 Workshop Manual, which you can download in six sections from the 'HOW TO' quick links thread of this forum.

The closest equivalent is U042600 which indicates "Invalid data received from vehicle immobilizer control module," just like the generic OBDII code U0426.

How did you obtain the code? With a Jaguar-specific reader like JLR SDD, or with a generic OBDII scanner? If you used a generic scanner, there may be additional proprietary Jaguar codes stored that may be helpful in diagnosing the issue. The U0426 code does not appear to be related to a coolant temperature issue.

Regarding your temperature gauge, perhaps there is a problem with your Engine Coolant Temperature Sensor (ECT or ECTS), or its electrical circuit (loose or corroded connector, shorted wire) or a problem in the network communication between the instrument cluster and other modules. If there are any Jag-specific codes stored they may give you a clue to the source of the warning lamp.

The X350 Workshop Manual I mentioned earlier gives definitions for the DTCs. The C codes are mostly in the Chassis section, the P codes in the Powertrain section, the B codes in the Body section and the U ("Undefined," or mostly network-related) are mostly in the Electrical section. I believe the X350 Electrical Guide is also availble for download but if not, send me your email address via private message with X350 Electrical Guide in the subject line and I'll email it to you in pdf format.

Cheers,

Don

 

Hey Don,
Thanks for all your info, I am just using a generic cheap scanner. I found same as you the U0426 is a "incomplete data" received by the VICM. I cleared the code and drove it a few miles and the light stayed on and no gauge reading. I came home and checked codes again and to my surprise had a P0116 code "ECT Circuit Range/Perforance Problem". I cleared that code and PINGO light out and gauge working again. I since have driven over 50 miles with mutiple start and stops with everything working right.

So for now I have fingers crossed and an eye open.

Thanks again Don

 

Great! Thanks for reporting back. Please keep us informed!

Cheers,

Don