Codes
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Joined: Jun 2012
Posts: 544
Likes: 239
From: Pennsylvania
P0420 could be several things. The code means Catalyst System Efficiency Below Threshold.
1. An exhaust system leak.
2. A bad O2 sensor
3. A bad Catalytic Converter.
Bank 1 is the drivers side. If you are lucky it will be the front O2 sensor, Bank1, Sensor 1. According to the book, it could be either on the drivers side and possibly the front sensor on the passenger side.
Worst case is the drivers side cat. That was my problem when I had the P0420 code.
Best to use a scan tool and actually watch the O2 sensors in action. You will be able to determine which one is at fault.
1. An exhaust system leak.
2. A bad O2 sensor
3. A bad Catalytic Converter.
Bank 1 is the drivers side. If you are lucky it will be the front O2 sensor, Bank1, Sensor 1. According to the book, it could be either on the drivers side and possibly the front sensor on the passenger side.
Worst case is the drivers side cat. That was my problem when I had the P0420 code.
Best to use a scan tool and actually watch the O2 sensors in action. You will be able to determine which one is at fault.
Pole Position
Joined: May 2016
Posts: 3,082
Likes: 653
From: AZ
Do a google search for "clublexus.com P0420 sc430"
The second O2 sensor (post cat) is the one that monitors how efficient your cat convertors are working
as for C1201, I would check your brake fluid and brake pads
The second O2 sensor (post cat) is the one that monitors how efficient your cat convertors are working
as for C1201, I would check your brake fluid and brake pads
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