Buy Now | Log In | ALLDATA Corporate Site |
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 View Factory Service Bulletins and Recall Titles Contact Us
Dowload Our Navigation Chart
February 2015: New vehicles added including 2014 GM.
• View New Vehicles
October 2014: Release of 2013 along with initial 2014 Vehicles
• View 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 users over the course of many years.
If you have any questions, please feel free to email us.



Lincoln - Mercury
  Jim Grant's Tech Tips

'00 Pontiac Grand Prix GT, Inefficient Converter Code?

Q: I drive a ‘00 Pontiac Grand Prix GT (3,8L Engine) and the "check engine soon" light came on today. I went to a local parts store for their free diagnostic machine and it reported that the problem was a “PO 420” The PCM has determined that the catalyst system efficiency for Bank 1 is below threshold for the current engine operating conditions. What does that mean? Oxygen sensor? I checked the gas cap and it was on tight. Could a bad air filter cause the problem?

- John T.

A: What does it mean? Each time you start the engine to your vehicle the computer runs
tests of the catalytic converter. If the converter fails the test the computer turns on the “service engine soon” light and will report the diagnostic code P0420. What this all means is the converter is not working right. A replacement converter may be needed but I would suggest a few diagnostic checks first. The vehicle’s computer uses information from 2 different oxygen sensors to compare the oxygen entering the converter to the oxygen exiting the converter. The sensor at the exit of the converter will read a different value than the sensor at the front of the converter. That’s because the converter uses up oxygen in the final phase of operation. If a sensor is not reporting to the computer correctly (lying) the computer could falsely fail the converter. Also, be aware that the exhaust cannot have any leaks. Exhaust leaks near the oxygen sensors can and will cause false readings. One last note, if your converter has failed check with your dealer. There is a time and mileage warranty on the converter and your vehicle maybe covered. Most of the time, all the dealer will need is your vehicle identification number and the mileage when you call to answer that question.

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