Buy Now | Log In | ALLDATA Corporate Site | AutoZone.com
Back To Home Page
Log In To Your Subscription
Go To ALLDATA Back Home
Buy A Subscription! Back Home About ALLDATA Information View Sample Vehicles Read Testimonials Frequently Asked Questions Contact Us
Dowload Our Navigation Chart

Sign Up To Receive ALLDATAdiy.com Alerts

Click Here to receive regular product updates, special offers, and automotive news.

2012 Subaru Now Available May 2013: More 2012 Vehicles Added including Fiat!
• View New Vehicles
2012 Subaru Now Available December 2012: More 2012 Vehicles Added including Chevy & GMC!
• View New Vehicles
View All News and Updates:
• Go To News
Tech Tips
  Read All Tech Tips

ALLDATA Tech Articles Are Updated Weekly
• View All Tech Articles

  Dodge Durango: Brake Pulsation Problems In Paul's Durango
• Read Dodge Article
 
Fixing A Smelly Audi Audi Tech Tip: A4 begins to Smell caused by a Faulty Hose Composition
• Read Audi Article
Why Do You Need To Change Your Timing Belt? Why Replace Your Timing Belt
• Read Belt Article
Jim Grant Tech Tips Jim Grant Tech Tips
A collection of helpful articles based on reader submissions
Home >> Featured Tech Articles >> Go Back
   
  Jim Grant's Tech TipsJim Grant's Tech Tips
Below is a collection of Jim Grant's Tech Tips sorted by Vehicle Make. These Tech Tips were answers to questions submitted to Jim by ALLDATAdiy.com users over the course of many years.
If you have any questions, please feel free to email us.
 
 

Miscellaneous
Acura
Audi
Buick
Cadillac
Chevy
Chrysler

Dodge/Plymouth
Ford
GMC
Geo
Hyundai
Honda
Isuzu

Jeep
Lexus
Lincoln - Mercury
Mazda
Mercedes
Mitsubishi
Nissan
Oldsmobile
Pontiac
Saturn
Subaru
Toyota
Volkswagen
 
   
  Jim Grant's Tech Tips

'96 Mercury Sable, OBD II Code P0420

Q: Can you tell me what OBD Code P0420 “Catalyst system efficiency below threshold (bank 1)” refers to? Is this an O2 sensor problem or does the catalytic converter need to be replaced? This is on my ‘96 Mercury Sable with a 3.0 liter V-6 engine.

A: The computer in your vehicle uses an oxygen sensor in front of and behind each converter. The converter processes and reduces exhaust emissions. The computer program knows that there will be a difference in the information being reported from the front O2 sensor and the rear O2 sensor as the converter processes the exhaust emissions. As a converter ages it becomes less efficient. This loss of efficiency is known by the computer because of the information that the O2 sensors mounted before and after the converter report. Just because you have a converter efficiency code doesn’t always mean the converter needs to be replaced. A defective O2 sensor can cause this code to be set by the computer as well. Your technician has to check the O2 sensors to be sure that they are operating correctly and that other related systems are doing their job. If all checks good then a replacement converter is needed.

 
     
Have any Questions About ALLDATAdiy.com? Please Email Us
Buy Now | Log In | About | Sample Vehicles | Testimonials | Join Affiliate Program