How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask The BMW Doctor Your Own Question
The BMW Doctor
The BMW Doctor, BMW Technician
Category: BMW
Satisfied Customers: 2427
Experience:  Over 30 years experience, 13 years with BMW, former BMW Shop Foreman, Service Manager
Type Your BMW Question Here...
The BMW Doctor is online now
A new question is answered every 9 seconds

what does code P0420 mean on the 2002 BMW 745LI?

Resolved Question:

what does code P0420 mean on the 2002 BMW 745LI?
Submitted: 7 years ago.
Category: BMW
Expert:  The BMW Doctor replied 7 years ago.



Thank You for choosing Just Answer for your query. Yes, I can help you.


P0420 - Catalyst System Efficiency Below Threshold (Bank 1). This indicates that the catalyst has failed. The Engine control module (ECM) compares the pre-catalyst and post-catalyst oxygen sensor values to determine it's efficiency. It has failed to meet the parameters.


The catalyst is part of the exhaust manifold on this year model BMW. They retail for about $12,70 (US) and would be about 6 hours labor to replace. If this vehicle has under 80, 000 miles on the odometer and is a US specification vehicle, it should be covered under the federal 8 years / 80,000 mile emissions warranty.


I hope I have answered your questions and addressed your concerns, should you have any more questions regarding this matter, please do not hesitate to ask. I want you to be 100% satisfied with this answer.


If you decide to accept this answer, please click the ACCEPT button by this answer.


Thank You!











The BMW Doctor and 2 other BMW Specialists are ready to help you