GTI6 16mpg?

[KevinTW]

My first bets would either be lambda or the green temp sensor on the thermostat housing.

I am fairly sure that when the green temp sensor detects the coolant is cold the car runs rich, and that if the sensor is faulty/unplugged then the car will just run rich all the time.

Frankly, at the age they all are, most sensors are either not working 100% or will be failing at some point in the near future if they are original so it is probably worth replacing both if you intend to keep the car for a reasonable length of time. That's just my opinion though

Thank you. £10-49 in Euro Car Parts. There was voltage at the plug when I put the ignition on. Just going to get it. Lambda ordered,air filter washed and dried,injector cleaner in the tank. Can anybody think of anything else?