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 Virtual Wrench Your Own Question
Virtual Wrench
Virtual Wrench, Chevy Mechanic
Category: Chevy
Satisfied Customers: 14620
Experience:  35 years Master Mechanic
Type Your Chevy Question Here...
Virtual Wrench is online now
A new question is answered every 9 seconds

1999 chevy suburban p0430 code showing low effiecintcy below

This answer was rated:

1999 chevy suburban p0430 code showing low effiecintcy below threshold catalyst system bank 2,thats passenger side manifold ? replaced both o2 sensors sel still comes back on?



Is that the only code coming up?

Customer: replied 6 years ago.
yes thats the only code coming up



In all the cases we have found the cat converter to be the cause of this. Make sure to replace it with an OEM unit. I have included the technical info on that code for you to read. Click here to download it.


Thanks for asking!





Customer: replied 6 years ago.

before this code came up a week ago had a missfire it was a bad distributor cap thougt it was bad gas then added a fuel conditiner then that code came up then replaced o2 sensors on passenger side code still shows up after driving 10 miles




The combination of the misfire and the additive is most likely why the code is set. You can try disconnecting both battery cables and touch them together for 10 seconds then reconnect them. This will reset the computer and hopefully the light will stay off. If not, then the converter will need replaced.


Best of luck my friend!

Virtual Wrench and other Chevy Specialists are ready to help you