P0420: A DTC Breakdown
A closer look at a common code, DTC P0420.
Code Reader Podcast: P0420 & P0430
This TSB was released by General Motors, covering most of their large SUV’s and vans that have been produced from 2002 and up. The related DTCs that a technician may find are P0420 and P0430, Catalyst Efficiency Below Threshold.
Code Reader: DTC P0420
DTC P0420 is stored when the readings of the pre- and post-cat oxygen sensors indicate that the catalytic converter is not working as efficiently as it should be in accordance with pre-programmed specifications.
Code Reader Podcast: P0420
TechShop’s The Code Reader Podcast takes common DTCs, breaks down when and why they occur and looks at symptoms and causes to help listeners make an accurate diagnosis.
VIDEO: Is the Converter to Blame? Diagnosing DTC P0420
TechShop Managing Editor Eric Garbe describes what you need to know when the scan tool is reading a diagnostic trouble code of P0420 Catalyst System Efficiency Below Threshold.
Pulling Codes: The Ghost of Code P0420
Every once in a while you come across a vehicle with a P0420 code that bears mentioning. Using one of his scan tool’s features, Carlton Banks tests the catalytic converter’s efficiency.
Volkswagen Tech Tip: Check Engine Light Is On With Fault Code P0420
If you encounter a check engine light on with a fault code P0420 stored in the fault memory, this may be the result of a defective catalytic converter.
Tech Tip: Volkswagen Check Engine Light is on with Fault Code P0420
If you find that the Check Engine Light (MIL) is on with fault code P0420 (16804) stored in the fault memory, the condition may be caused by a defective catalytic converter(s). If any other fault codes are present besides catalyst (CAT) faults, the other codes must be addressed and corrected before proper/complete CAT testing can be performed.
Tech Tip: Nissan DTC P0420 Stored in ECM
If you confirm DTC P0420 (Catalyst System Efficiency Below Threshold) is stored in the ECM, determine if this bulletin applies by checking the ECM part number.
Catalytic Converter Tech Feature: Diagnosing P0420 or P0430 DTCs
Although modern OBD II technology has simplified catalytic converter diagnostics, it’s still important to understand the basics of catalytic converter operation when dealing with a P0420 or P0430 DTC. Gary Goms explores the basics of catalytic converter chemistry and summarizes how common converter failures can be diagnosed.