CarScan

What do these codes mean together?

Paste the list of codes your scanner gave you. We explain each one and — more importantly — what they mean together: several codes often come from one cause.

Paste anything: a list with commas, lines copied from another app, words in between. We will find the codes ourselves.

What they have in common

This is the part a per-code reference cannot tell you.

Each code

P0420Catalyst system efficiency below threshold (bank 1)

The catalytic converter works below par. Before replacing it, make sure the second oxygen sensor is fine and there is no exhaust leak — those get replaced far more often.

P0171System too lean (bank 1) — air leak or not enough fuel

Most often this is an air leak: cracks in the intake hose after the air filter, a hose that slipped off, a tired gasket. Less often — a dirty mass air flow sensor or a weak fuel pump. Start by looking at the hoses, that costs nothing.

How to put together a report a mechanic will actually read

A list of codes is a symptom, not a diagnosis. It says which checks failed, not which part to buy.

How the app helps

CarScan reads these codes from your own car, shows whether each is active right now or only stored, adds the live readings behind them and puts everything into a report for a mechanic.

See what the app does