× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network

P0420 Diagnostic Trouble Code Discussion for November 2005

Catalyst Efficiency Below Normal (Bank 1)

Note: This is a professional automotive technician's resource.
Vehicle Owners: If you are seeking an automotive repair professional to service your vehicle, visit the iATN Repair Shop Finder.

Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1999 Chevrolet Blazer 4.3L MIL Lamp on, P0420 VIN: 1GNDT13W0X
P0420: Catalyst System Low Efficiency (Bank 1). This ought to be a "no brainer", but since I never saw any data from the oe cat, I'm not sure where to go from here. My customer told me the installer told her he didn't think it was the cat due to its' ( good ? ) condition, but he replaced it anyway w...
November 08, 2005
1998 Honda Civic DX 1.6L MIL Lamp on VIN: 2HGEJ6340W
P0420: Catalyst Efficiency Below Threshold (Bank 1). ... had a catalyst efficency code that we diagnosed in Sept.- customer declined a new cat at that time- He came back this week and had a reman? cat installed at a muffler shop- his light came back on for the same P0420 code and the muffler shop replaced it aga...
November 16, 2005
2000 Mazda Miata 1.8L Misfire, MIL Lamp on VIN: JM1NB3532Y
P0420: Catalyst Efficiency Below Normal (Bank 1). ... and 'check engine' came on . Code p0300 ,p0420. Misfire occured after hot soak(it act up to me once and I see no spark at coil on # 1 cyl ). I replaced a set of wire due to burn at cyl# 4. Gave car back to customer and he came back 4 weeks later with same ...
November 22, 2005
1997 Toyota Tacoma DLX 2.4L MIL Lamp on VIN: 4TANL42N5V
P0420: Catalyst Efficiency Below Normal (Bank 1). Started with P0420, cat eff. code. Checked front and rear o2's.Rear mimiced front.Replaced cat. Same problem. Looked at front and back oxygen sensors. Front has great movement. Rear has none until RPM reaches 2500 then it mimics front. I checked both waveforms...
November 30, 2005