Hey guys,

I've got a check engine light on my 2011 jaguar XFR, it is for catalytic converter efficiency low(bank 1). Shop is telling me I need a new cat, obviously fairly expensive from jaguar. Mechanic also mentioned if I go aftermarket cat it may throw more codes, what do you guys think? Aftermarket cat would save me a lot of money. Or anyone with a cat laying aroind they want to sell? Lol Thanks guys.

 

No, the new cat shouldn't throw any more codes as long as it's of sufficient size, but you do need to find out -
If the cat is truly bad? It could be a lazy (Bad) O2 sensor.
If the cat is bad, what caused it's demise before you send a new one to the same fate, Usually a bad pre cat O2 sensor as it's the one that tells the Engine Control Computer how much fuel to give the engine. The post cat O2 sensor just turns on the light if it see's a wrong fuel ratio OR if it's gone bad, but things like coolant tn the exhaust stream can kill cats too?
Be nice to know the mileage on your XFR?
Are their any other codes?
Most don't realize O2 sensors need to be changed about every 80kmi to 100kmi, they get slow to respond to a changing air to fuel ratio, then the computer gives a wrong fuel needs command and now you overheat a cat and need a new one. So it's very important to find out what killed your cat in the first place.

 

Hey BW, you said, “Most don't realize O2 sensors need to be changed about every 80kmi to 100kmi, they get slow to respond to a changing air to fuel ratio,”, is this a fact? I’ve never heard of this before. And with the price of o2 sensors today, damn!

 

I've read it more than once but it's possible it was true originally and now isn't. Not sure how one would prove it either way!

 

Slow responding o2's is a problem that the ECM should recognize today isn't it? I seem to recall seeing that in the list of codes somewhere...

 

There will be a range where it's OK and eventually where it's not, most likely.

If I could see when it was well out of the central good range I'd change it - but such readings are not available I believe.

I just wait till one actually fails but also I log MPG over the years and in addition occasionally (well, roughly annually) check fuel trims. If nothing seems amiss I leave well alone.

 

Not always, my 2003 G35 Sedan burned off the whole tip of an O2 sensor and ran fine with no codes until I changed it and saw it.

 

O2 sensors are just like any other wear item on your car, the government mandates on new cars they be warranted 80kmi. After that you're on your own, and while they are expensive, 4 every 80kmi isn't too bad if you shop early. I've had a set for my XFR since 75kmi, I'm at 91kmi now, gonna change them at 100kmi. Waiting for them to go bad can mean death to a cat.