What is a code p2181 and no do I trouble shoot it

Originally Posted by agental@http://newbeetle.org/forums/2-0-liter-gas/5464-recurring-code-p2181-cooling-system-performance-2.html basically P2181 means the ECM didn't see the engine warm up fast enough or it warmed up TOO fast(water pump impeller is jacked). When a car comes to me with this problem I automatically replace the water pump, thermostat, and ECT. I've done this repair and all 3 pieces look to be in good working order so don't assume you can inspect the parts and see which one is broken. I wouldn't trust aftermarket parts either(except for the water pump, plastic impeller sucks). Never had one come back for this.