EPC Light - Intermittent display

I have a PD130 which is 3 1/2 years old, done 67k. Over the last few weeks the EPC warning light (engine shaped) occasionally displays. According to the handbook this says it puts the engine in safe mode, but there is no evidence of this - it remains as lively as before!

I am concerned because last year I had the typical 'Passat water problem' of soaked carpets which was remedied by my local dealer by carrying out a modification to the drainage tubes under the battery and am now wondering whether there may be some residual corrosion of some terminal/joint in the loom?

This is also coincidental with erratic behaviour of the drivers side puddle lights/interior light function.