BECOME A MEMBER
Sign up with Facebook
I agree to the
Login with Facebook
NOT A MEMBER?
P Codes (powertrain)
P0400 - P0499
Diagnostic shows P0420, how do I repair that.
1997 MERCURY MARQUIS
Catalyst system Efficiency Below Threshold Bank 1 is what shows up. Took it in auto zone did a diagnostic and showed cadalack coverter. But today showed the P0420
have the same problem?
Friday, June 8th, 2012 AT 4:36 PM
Best to have a pro look at it. It can be a converter bad, a coolant leak cooling off the converter, a bad O2 sensor, many things.
Please consider a donation if we helped you
Friday, June 8th, 2012 AT 4:48 PM
to post a reply.
Related P0420 Questions
Po420 On 2000 Grand Marquis
I Recently Had The Po 420 Code Show Up On My Grand Marquis. I've Replaced The Downstream O2 Sensor On Bank One. It Didn't Fix The Problem...
Ok Ok, Let Me First Start By Saying Many Of You Have Been Helpful In The Past And Hopefully Will Come Thru For Me Again.I Have A 97 Grand...
Also Forgot To Add To Last Post That While I Had Codes P0171 And P0174 Showing A Lean Condition, I Cleaned Maf Sensor. This Seemed To Make...
1998 Mercury Marquis Diagnostic Code P0430
Computer Problem 1998 Mercury Marquis V8 Two Wheel Drive Automatic 239000 Miles Code P0430 Keeps Engine Light On All The Time. Have...
Ask a Car Question. It's Free!
Fuel Injector Replacement
Mass Air Flow Sensor Replacement
Fuel Pump Replacement Toyota Tacoma
Find a car manual for your car
© 1999 - 2017 2CarPros, Inc.