Check engine light after Fast Intentions TP install

Originally Posted by fryzia23

TP or HFC will throw codes for downstream sensors but it should not effect upstream. If it comes back immediately it means most likely theres an open circuit so either the sensor itself or wires got damaged or simply the sensor could be not connected.

Originally Posted by Rusty

Chances are that when they removed the old cat's. They used an air impact gun on the bolts. IF they did not remove the the O2 sensors before using the air imact gun. The vibrations from the gun WILL damage the O2 sensors. The first thing you do is to remove the sensors. The last thing you do is install the sensors. So many people here on the forum have run into the same problem with the sensors. Nobody learns.