Catalytic converter
Catalyst efficiency below threshold. P0420 is the second most common code overall and is very often a lambda sensor rather than a dead catalyst.
5 documented codes across 47 real diagnostics.
Ranked by how often we actually see them
FAQ
Frequently asked questions
How do I run a diagnosis?
Select the vehicle on Start, click the Diagnostic card and choose New diagnostic. Fill in the description, the error codes and the mileage, then click Analyze.
Learn more: Diagnostic (vehicle-first start), Diagnostic form: description, error codes and mileage
Do I have to type the codes from my scan tool?
No. Click the camera button next to Error codes and take or choose a photo (JPEG or PNG) of the scan tool's screen; WrenchLane reads the codes and their descriptions into the form. You can also speak them with the microphone.
Learn more: OBD reader photo scan (fault codes from a photo), Voice input for the problem description
Are the public fault code pages built from my diagnostics?
They are built from anonymised, aggregated diagnostics run in WrenchLane; no workshop, customer or vehicle can be identified. Each fault code page shows how often the code was seen across those diagnostics and in how many separate workshops.
Learn more: Fault code pages on wrenchlane.com (fault-code cluster)
Work a catalytic converter fault on a real car
Enter the codes and the symptoms and get ranked probable causes for that specific vehicle, with the checks in the order worth doing them. Free account, no card.
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