The P0420 diagnostic trouble code indicates that the catalytic converter on Bank 1 is not operating efficiently.

In simple terms, this means the catalytic converter is not properly reducing harmful exhaust emissions.

When the P0420 code appears, your Check Engine Light will turn on.
In most cases, the vehicle may still drive normally, but the issue should not be ignored.

P0420 is one of the most common emissions-related trouble codes worldwide.

The P0101 diagnostic trouble code indicates that the engine control module (ECM) has detected an issue with the Mass Air Flow (MAF) sensor performance.

This means the MAF sensor readings are outside the expected range compared to engine load, throttle position, and RPM.

When the P0101 code appears, your Check Engine Light will turn on, and the vehicle may experience reduced performance, rough idle, or poor fuel economy.

P0101 is one of the most common airflow-related OBD2 trouble codes worldwide.

Here are standard and unique error codes for the Citroen Ds3, received through the on-board diagnostic connector of the OBD-II system of the car, with a brief decoding.

The P0171 diagnostic trouble code indicates that the engine control module (ECM) has detected a lean air-fuel mixture on Bank 1 of the engine.

In simple terms, this means the engine is receiving too much air and not enough fuel.

When P0171 appears, your Check Engine Light will turn on, and the vehicle may begin to run rough, hesitate during acceleration, or consume more fuel than usual.

This is one of the most common OBD2 codes on gasoline engines worldwide.

The P0300 diagnostic trouble code indicates that the engine control module (ECM) has detected random or multiple cylinder misfires.

When this code appears, your Check Engine Light will usually turn on, and the vehicle may run rough, shake, or lose power.

P0300 is one of the most common OBD2 codes found on gasoline engines worldwide.

The P0299 trouble code indicates that your vehicle’s engine control module (ECM) has detected that the turbocharger is producing less boost pressure than expected.