New CAT replacement recommendations

Technical Area Engine, Transmission, Exhaust etc
1

Hi, I recently purchased my first 2003 mk2.5 mx-5 and after a week the engine light was switched on. Garage has told me the CAT needs replacing, I was wondering if I could please have some advice on solid replacements, not looking for anything cheap just something that will be reliable and last me a while.

Thanks,

Henry

2

Anything “OEM grade” will do you. Chances are that it’s the original catalyst that died, so 23 years isn’t bad going.

3

Welcome to ownership from fellow Mk 2.5 [2005] owner in Staffs :handshake:

4

Fitted a BM Cats cat to our Mk1 about 7 years ago after it failed emissions on original cat.

Still passing tests on the replacement but needing more coaxing with a longer hotter drive directly before test.

Probably need a new replacement in next year or so, but not done too badly.

5

Since the car is post March 2001, it needs to be a type approved cat. (The BM one in the ebay listing above isn’t, but they do sell them).

I’ll need one soon, and am torn between buying a used cat from a low-ish mileage breaker or a new, type approved BM one.

6

Out of interest, Ive got an nb with old cat, but how do you know it is the cat that is causing the engine light to show?

7

Welcome to NBFL/2.5 ownership.

Since the car is new to you there are a number of things I would do before pulling the trigger on a new cat.

  1. get an OBDII reader and down load some software for it to your phone and see what fault codes emerge. They will help diagnose the fault/s causing the EML light to come on.
  2. Check the fault does not lie with either of the two cat O2 sensors.
  3. See if a catalyst cleaning addative will fix the problem.

When you are sure the fault lies with the cat and nothing else only get a type approved cat , I have not experienced the BM one but it has been mentioned positively here before.

Being a bit of a nut case and having determined my 02 NBFL is my forever car soon after being given it 8 years ago, when I concluded mine needed a new cat six weeks ago I went to my local dealer and was pleasantly surprised to find I could order a new one, eye wateringly expensive yes, but even if it, and I, only last another ten years I will have had my moneys worth.

I was given a six week delivery time as the item had to be ordered from the factory, and despite all the chaos that has unfolded in the world since ordering it I was delighted to get a call from Millcars to go and pick it up yesterday.

If you have any further questions regarding the OBDII or anything else do not hesitate to ask, these are great cars and well worth persevering with.

Wishing you many smiles per mile.

8

Roughly how much (if you don’t mind)?

(I know used ones were fetching ~ÂŁ2k a few years ago when the rhodium price was high.)

9

A bit more than used ones a few years ago then :wink:

10

I went through half a decade of marginal, barely passing emissions with after market cats. Utterly acing emissions now with a 30 year old rusty factory catalytic converter.

11

Thank you for the advice, do you know of any specific type approved CATs that are available or any sellers to reach out to ?

12

I’m currently going off the advice of my garage, and nearly failed my last MOT for high emissions but may have to look for any potential alternative issues causing the engine light such as mentioned on this post the O2 sensors

13

Thank you for the reply, do you know which factory or supplier your garage sourced your replacement CAT from ? And also what would be some indicications the problems lie with the O2 sensors, rather than the CAT itself, thanks :slight_smile:

14

I know that BM make type approved ones, and that they’re available on ebay.

I remain sceptical about the quality of all aftermarket cats though!

15

AS Art mentioned, I’d be putting CataClean or equivalent in the tank, then checking the O2 sensors all before replacing the cat itself.