You have bad cat; how is replacing the O2 sensor going to clear that???

 

When I asked the service rep if he thought that by replacing the O2 sensor the check engine light might go away he advised me that there has been instances were replacing the O2 sensor has removed the notorious P0420. I decided to roll the dice, take the chance and spend 25 oppose to 800, for now. We will see.

 

I need to understand the logic here...

The rearward O2's job is to report a potentially bad or faulty catalytic converter; your existing O2 did this.

So like many of us would do, you got it profesionally diagnosed by a Ford service tech, who told you the catalytic converter was bad. You paid for that diagnosis I assume?

And now, You will spend $25.00 more for a new rearward O2 to set a code that it detects a faulty catalytic converter.

Maybe after three times that you are informed the catalytic converter is bad, you will replace it?

 

this. The sensor is working alright as it picked up on the catalyst below efficiency. If the sensor itself was bad you would have a code for the sensor out of range or a complete failure. Not a P0420

 

The diagnosis at my local Ford dealership was actually complementary and yes, if and when the Check Engine light returns I will be forced to spend the 8 to $900 dollars.

 

it will return

 

did it return?

 

Actually the light did return! : ( it was going strong until Sunday this past weekend.....I am now debating on whether to buy an OEM catalytic converter for $800 or one from eBay for about $230. Any thoughts out there on the quality of a passenger side eBay direct bolt on catalytic converter for a 5.4L 2008 Ford F-150 crew cab?

 

I have been looking at the eBay one myself.. but then again I did not inspected my issue to the full extent.

 

I'd definitely be looking for other options then $800 for an OEM. Good luck. Keep us posted.