Check engine light.

[ford griff]

Getting a check engin light 420 01/01 ,manifold catalyst efficiency low (bank1 ) how can I figure out if its the right side or left ? And is there any way to test the sensors ?:rangertan:

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the EEC-V section. What are the code numbers (they start with a Pxxxx)?