Hey guys,

Jaguar S type 2000 Engine 3.0 V6

DTC Error code - P0420 - Bank 1 catalyst below Threshold

Any suggestion for Catalytic converter?

Which BRAND?? Part number? its on Right hand side, right?

I am really confused about which one to buy, The local AUTOSHOP asked me $260 for UNIVERSAL !!

Suggestion needed!!!!!!!!


Thnakssssss!

 

What is your tolerance for gambling on an inexpensive fix first, before pulling the trigger for a new cat?

You may find this thread of interest, although be aware it was for a 2003+ car, which has more advanced oxygen sensors than the early models. Initially the thread was asking about using a spacer to move the downstream oxygen sensor out of the direct exhaust stream, in hopes of a cleaner reading. The thread eventually devolved into a bunch of chest-thumping, name calling, and I think even included me being outed as a BeeGees fan, but hey, that's life on a forum:

https://www.jaguarforums.com/forum/s...x-hmmm-151396/


My thoughts on the first thing to try for a P0420 code? I'd suggest the upstream sensor, not the converter itself. $30 versus several hundred dollars, with a very good change of a fix. Call me Mr. Vegas, but I think it's worth a gamble. From post #6 in that thread, copied for your convenience. For a bit of context, the original poster had installed a new downstream oxygen sensor, but I think you want to keep the old one there and install a new one in the upstream position:

"Catalyst efficiency is determined by comparing the switching rates of the upstream and downstream sensors. The upstream sensor sees the "raw" exhaust. The PCM constantly keeps adjusting the air/fuel ratio at a very rapid rate, and the upstream O2 sensor values should reflect this rapid switching. Meanwhile, the downstream sensor sees the "clean" exhaust after the catalytic converter. If the converter is doing its job, there shouldn't be much switching downstream, just a fairly steady value. If the converter has failed, both sensors will rapidly switch up and down together, because no cleaning action has occurred passing through the converter.

As O2 sensors age, they typically don't respond as quickly. Since a slow switching rate downstream is actually good, you're better off with an old sensor there. By the same logic, a new sensor upstream is also good, to increase the difference in switching rates that tells the PCM the converter is working. By installing a new sensor downstream, you have inadvertently created a situation opposite of what you want.

If you still have the old sensor, I'd suggest reinstalling it downstream and then installing a new sensor upstream. I believe the sensors are the same except for the length of the wire pigtail. You may be able to swap the old upstream and new downstream sensors if the connectors will reach, but am not sure. I'm always leery to suggest just throwing parts at a problem, but upstream sensors are normal wear and tear items and should be replaced periodically anyway, so I won't feel bad if it doesn't fix the problem.

Also, keep in mind the P0420 code typically does not come on right away. I believe it has to be seen on at least two consecutive drive cycles to prevent nuisance messages. A scan tool will show the code stored as pending, but won't turn on the light until it sees the fault on the second consecutive cycle."

End of copied message.

FWIW

 

Below is the cylinder numbering scheme for the Duratec V6.

DTC P0420 is for Bank 1, which is on the RH side of the engine when viewed from the driving position.

In my experience, P0420 can only be corrected by replacing the catalytic converter for Bank 1. Be sure you check local emissions regulations for aftermarket catalyst fitment as some jurisdictions follow stricter codes making non-certified parts an offence to fit to a vehicle registered and operated in those jurisdictions.

 

Rock Auto carries Eastern Catalytic and Davico brands. No personal experience with either, but I vaguely remember one forum member being very pleased with Davico:

https://www.rockauto.com/en/catalog/...converter,5808

Also, I noticed you had another open thread asking about some other codes. I'd suggest taking care of those codes and then coming back to the P0420. Problems elsewhere could be affecting the calculations that trigger this catalyst efficiency code.