So these are the codes that was detected. I got these from Autozone.
P0420 - Passenger air bag firing circuit 1 (resistance too low)
Catalyst System Efficiency Below Threshold (Banke 1)
Secondary DTCs
P0328: Knock Sensor 1 Circuit high input (Bank 1)
P1111: System check complete Since Last Memory Clear



I mentioned that I suspected it may be the catalytic converter. When I drive it rides fine. Then, as I accelerate the message reads "Performance Restricted" w/ a yellow light. The Engine light has always been on when I got the car. I noticed when the message is on. The RPMs would be stuck around 2000 (idk if this is normal or not lol) but it would struggle to accelerate.

To the knowledgeable forum...what should be the next plan of action? I was convinced I need to change the catalytic(s) but you know it $$$

Thank you all.

 

Well, I am not surprised that the diagnostic tests from a parts house tells you that you need parts...

What do your fuel trims look like? Every modern Jaguar owner needs to have a diagnostic code reader that has the capability to display fuel trims, etc. in real time.

The knock sensor is part of the system that allows the PCM to regulate the ignition timing on your engine; it may be significantly retarded as a default to protect the engine from pre-ignition.

Also, there is kind of a mantra around here: Replace the cheaper parts first....

 

What do your fuel trims look like?

I have no idea lol but I will look into this now that I'm aware. As I was posting my codes I stumbled upon some similar threads and it mentions a knock sensor. I'll look into getting a diagnostic device (suitable for the Jag) and get back with you.

Thank you and great advice...cheaper parts first

 

The Pass. air bag is utterly wrong. P0420 is about the cat - or something causing a misleading reading, so may not be the cat.

Sort out the knock sensor and see if things change.

 

Yes they have major errors in that listing as JagV8 said. I would get another scan done with a different scanner? Just to be sure as cats are VERY expensive right now. You probably have seen all the news about converter theft too.
As always be sure and clear all the codes to check what comes back and what might be just a "historical" code.

Also note you currently have P1111 which means all clear to get your car inspected as all the driving monitors have been set. After clearing the codes you will have a P1000 code and then after driving for some time that will reset to P1111 again as the driving monitors complete one by one.
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Ok great and I'm convinced its the knock sensor. Poor engine performance, bad fuel economy, and I did listen to the engine and I believe I do hear some knocking. I'll replace the sensor and go on to the next step as clubairth 1 suggested. Just waiting to get some money.

 

Prior to a lot of guesswork involving mental gymnastics and parts replacing, check the available battery voltage to eliminate low voltage as the cause of random DTCs.

Use a voltmeter to read voltage across the battery terminals with the ignition in the OFF position. There should be a minimum of 12.6 volts available for all modules to function correctly.