My 2013 Leon 1.8 FR engine light came on within 100m from a cold start one morning. When checking the codes it had the following single code. 15462 - Control Circuit for Coolant Bypass Valve P2681 00  - Open Circuit After checking for a loose connector and clearing the fault it didn't return on a later test drive. I put this down to VAG cars being fussy as all VAG cars I've had have random sensor circuit glitches. The next day we tentatively drove 330 miles on holiday. No problem at all. The following day the engine light came on again on start. Assuming it to be the same glitch, we drove a short distance. Not in limp mode and engine running fine. We stopped for a short walk and then restarting the car the engine light still on but accompanied by the EPC light and a warning on the display saying engine performance limited to 4000rpm. I took this to be proper limp mode and decided as in the middle of nowhere to limp back to the holiday house to read the codes/find a garage etc. However by the time we had reached the bottom of the hill after coasting down the engine temp was above 1/2 way which is not normal. Even without a proper diagnosis I was sure that the bypass valve must have jammed so stopped immediately and called RAC. They though it was either thermostat or water pump. Car taken to a Seat main dealer for diagnosis as could not be repaired. The prognosis was thermostat housing/water pump needed replacement at £700. This ended up taking all week of our holiday as after replacing the parts the car was still playing up. It turned out that inside the housing the bypass valve (electronic thermostat, whats wrong with a normal one?) is controlled by a motor. The gear on the motor shaft had fallen off and as the valve didn't open/close the motor kept running and this burnt out the wiring loom right back to the ecu. This is a design flaw in many ways. ie the gear should not fall off. The wiring should be protected with a fuse, and thick enough for prolonged operation. This was on a 40000 mile car. This code warning and failure was preceded by a slight drop in coolant in the reservoir without any obvious leak (not sure if this was actually related). If you get this code be warned that it could end up much more serious and ruin your day/holiday. Car has been absolutely fine since repair. From what I read about the 1.8TSI its supposed to be a good engine, but this is the 3rd ECU light event on ours over the last 5 years. 1st was inlet valve failure, 2nd random single misfire event. (water drop in fuel?). Having just spent an amount on repair, I was gutted to just read another thread about DSG failure at 45K. Time to trade in?