2018 VW Tiguan 162 - Waterpump/Thermostat - ERROR: P2681 Engine Coolant Bypass Valve

[Tiguan_RLine]

Hi everyone,


A bit of backstory: we've owned this car since 2020 (second owner), purchased it for 44k with 40k on the clock, and haven't had a single issue until now (72,000km). Two weeks ago, my partner, who primarily drives the car, called me to say the engine light had come on, and the engine had de-rated itself. She parked it at a local shopping center. The following day, I checked it and plugged in my OBD scanner, revealing the code P00B7, indicating "Engine Coolant Flow Low/Performance." I observed the coolant level just above minimum and noticed the temperature gauge fluctuating between 90°C and 117°C, prompting me to consider the thermostat.


After some online research, I discovered this is a common issue (VW has updated this specific part multiple times). I contacted several mechanics for quotes, all exceeding 3-4k, with the earliest availability in late December 23. Given the urgency, I decided to tackle the job myself, despite being a non-mechanic.


I contacted a local dealership and purchased a new Thermostat housing, Water pump, belt, and union for $1300, and they had it in stock—great! With help from a friend and their hoist, we began the teardown. After removing the underbody plastics, it became evident that coolant had been leaking (see photos), confirming we were on the right track.








I found a step-by-step video on YouTube (Don't Overpay for a MK7 Waterpump/Thermostat Housing and How to do it Yourself - YouTube), and we followed it precisely—removing hoses, clamps, undoing clips, unbolting brackets, and so on. Although more involved than initially thought, we pressed on.


The entire job took us 10 hours to complete.
Job completed and the thermostat is working great, temperatures are stable at 90°C.


However, we encountered a few new errors. P0340 Camshaft Position Sensor "A" Circuit surfaced, and after a few more hours of investigation, we found a forgotten connector. Issue resolved—great!





Now, a week or so later and the car still not being used, I'm desperately trying to diagnose P2681 Engine Coolant Bypass Valve Control Circuit/Open. If i clear the code, It doesn't disappear - However it does remove engine light which wont come back until the car is locked and restarted.

This one has me stumped, and I can't find much information online.



Any help would be appreciated!

[MIG]

That might be the N82 shut-off valve; I'm pretty sure the 1.8 is in the same location as the one pictured here Injection system engines 2,0 EA888 - Overview of fitting locations

I would be checking if there is voltage at the valve connector