A P0420 code for a 1999 Mercury indicates that the vehicle's onboard diagnostic system has detected a problem with the catalytic converter's efficiency. Specifically, it suggests that the converter is not performing as expected in reducing emissions. This could be due to a faulty catalytic converter, damaged exhaust components, or issues with the oxygen sensors. Diagnosing the exact cause typically involves inspecting these components to ensure they are functioning correctly.
NO Emission control only, does not affect performance.
Trouble code P0441 means:Evaporative emission control system incorrect purge flow
Trouble code P0441 means:Evaporative emission control system incorrect purge flow
you have a fault code on emission systems
manufacture control aux emission controls
Trouble code P0453 means: Evaporative Emission System Pressure Sensor/Switch High Input
Trouble code P0441 means:Evaporative emission control system incorrect purge flow
Trouble code P0441 means:Evaporative emission control system incorrect purge flow
Trouble code P0420 means: Catalyst Efficiency Below Normal (Bank 1)
Trouble code P1320 means: Distributor Signal Interrupt
Trouble code P0446 means:Evaporative emission control system vent control circuit malfunction
there is a "wallet card" which has the code on it, if you do not have this card you will need to bring the car into a Mercury dealer and they will "plug it in" and retrieve the factory preset code.