my 05 jaguar s type. When this happens the car goes into "limp mode" high rpm no acceleration. Sometimes turning to car off and on temporarily resolves it but largely letting it sit is the only "fix". It caused the check engine light to come on and I took it to jaguar. They replaced the battery, no help. They said the sensors were fine and suggested I replace the ecm even though it tested good as well. Recently my rpm fluctuate at between 25-40 miles. Any ideas?

 

Welcome to the forum bigdaddi1314,

The Jaguar Dealer suggested you replace the ECM! I would be wanting some very convincing diagnosis backed up by relevant error codes before considering that as a course of action.

When you get a minute, please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see.

In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

When "this happens" - what?

If it's battery related, measure voltage, before starting, after car sits overnight. New does not necessarily mean good so measure

 

Excellent advice from Graham, once you've done that what exactly happens?
Have you had the codes checked and if so what are they?