P0420 Saturn - Catalyst System Low Efficiency Bank 1
Repair Importance Level:
Repair Difficulty Level:
- Three way catalyst converter Bank 1
- Exhaust tube
- Intake air leaks
- Fuel injectors may be faulty
- Fuel injector leaks
- Spark plugs may be faulty
- Improper ignition timing
- Powertrain Control Module (PCM)
As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.
When is the code detected?
If a condition exists which causes the Powertrain Control Module (PCM) to detect excessive Bank 1 HO2S #2 activity outside of an acceptable range for an extended period of time, the PCM will set the P0420 code. This indicates that the three-way catalytic converters oxygen storage capacity is below a threshold considered acceptable.
- Engine Light ON (or Service Engine Soon Warning Light)
P0420 Saturn Description
In order to maintain a reasonably low emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), the engine controls system uses a three-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas. This reaction converts them into harmless water vapor and Carbon Dioxide. The catalyst also reduces NOx, converting it to Nitrogen. The Powertrain Control Module (PCM) monitors this process using Bank 1 HO2S #2. Bank 1 HO2S #2, located in the exhaust stream past the three-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively. If the catalyst is functioning correctly, the Bank 1 HO2S #2 signal will be far less active than that produced by Bank 1 HO2S #1.
Need more help?
Do you need more help with the P0420 Saturn code? ask a question to our users or search the top hand picked automotive forums for more information
SATURN Technical Service Bulletins for P0420 code
2006 SATURN ION Engine And Engine Cooling:exhaust System Details
2006 SATURN ION 063000 Engine And Engine Cooling:exhaust System Details
Repair Shops Around Your Area
Need parts to fix this code? Search hundreds of stores at the same time and compare prices
Help us improve Engine-Codes.com. Leave a comment below or tell us if the information above help you fix the code. What are symptoms is your vehicle for the P0420 Saturn code? Have you replaced any parts?
Any information is appreciated. Thanks