Passat (B5) :: 2002 / 1.8T - Knock Sensor Code 16711 (P0327)

So a letter history about the car and this car is a friends car. They owned the car and drove without changing the timing belt when the car hit 109k. So the timing belt snapped and they went out and bought a timing belt and also the timing belt kit with the pulleys and all. They installed it.. didnt turn over or what so ever.

They towed the car to us which we own an auto repair shop. We knew the valves was bent and so we tore off the heads send them off to have them put new valves and etc etc.. We put the car back together for them and now the car runs fine. They pick it up and about a few days later they brought it back due to a check engine. It threw the code:

16711 - Knock sensor 1-G61 Signal too low. (p0327)

now we replaced both knock sensors and when they came and got the car... the check engine light came back one showing the same code. We cleared it out and the next day it came back on showing the same code Again! So now we don't have a clue why that code keeps coming up because we replaced both sensors with a new one. Any clue why the code keeps popping back up?