2004 Ford KA diagnostic error p0420

STEPS TO DETERMINE THE DTC

DTC P0420 - Catalyst Low Efficiency




Step
Task
Positive
Negative

1
Ensure an EOBD System Check.

Task Over?
Follow Step 2
Follow "On-Board Diagnostic System Check"

2
Insert a scan tool to the Data link Connector (DLC).
Turn ON the ignition.
Can you see any component DTC set?
Follow applicable DTC table
Follow Step 3

3
Undertake a Visual check of the following:
a) Exhaust system for a leak.

b) Heated Oxygen Sensor (HO2S).

Task Over?
Follow Step 4
Follow Step 5

4
Work on the exhaust system as needed.

Job Accomplished?
Follow Step 6
-

5
Change the Three Way Catalytic Converter (TWC).

Job done?
Follow Step 6
-

6
Unset all DTCs taking a Scan Tool.
Start the engine and idle at normal operating temperature.
Operate the vehicle within the specified conditions for setting this DTC
Do you see the scan tool confirming that this diagnostic has been operated and the test passed?
Follow Step 7
Follow Step 2

7
Check if any additional DTCs are set.

Are any DTCs displayed that have not been diagnosed?
Follow Applicable DTC table
The system of your vehicle is fine.