January 2015: Brought a 54 plate RX8 with 55K miles for £1100 - so generally quite happy with that, took it in for a service at Halfords and spent £300 (inc servicing price) on 3 new tyres and an oil change.

March 2015: EML light come on & stayed on, again took it in to Halfords they done a diagnostic (P0420), cleared the light and charged me £50, the next day the light came back on and has remained on since.

June 2015: Decided to get new brake discs and pads all round from Halfords (did come up as a concern on previous service) charged £440, I also enquired about the CAT replacement (as I've found one on a website for £150 inc VAT) and they have quoted me £328 for that and then Lambda sensor replacement as part of that for another £253? Now considering this light has been on for a few months now there doesn't appear to be any issues driving it with and I have also seen plenty of other posts saying pretty much the same.

So I have 2 questions 1: Are Halfords ripping me off, would I be better off getting a quote from a back street garage? and 2: What are your thoughts regarding the CAT, I'm assuming if I don't sort it out then I'll eventually get a blinking EML light and would obviously have to get it done then?

 

1) second opinions don't hurt, but not many back street garages know much about RX8s. Usually we try to find a garage that's recommended by other rotary owners. Mazda dealers are a good option usually. There are exceptions

2) you have 2 modes of cat failure:
- where it's no longer effective at cleaning up hydrocarbons from the exhaust. You won't pass inspection that way, but it won't hurt anything except the environment.
- where the actual catalyst element is destroyed or blocked and creating a restriction in the exhaust system and slowly killing your engine through increased heat and pressure

Usually case 2 includes case 1.

You'll want to get it visually inspected (like taken off the car and looked at, preferably with pictures for the kind folks here). You cannot just replace it with some random off the shelf catalytic converter, it won't last 2 weeks on this car. You need the Mazda part to be safe, and it's expensive (if bought new.. used is another story). You also don't need to replace your lambda sensor unless they believe the sensor is actually broken.. but if it's broken, they shouldn't be replacing the cat based on that sensor's readings. So one or the other, but only both if one doesn't fix it ) That's where it feels like they're not working in your interest, but maybe they have other codes (say 02 sensor heating circuit).

The brakes, that just sounds excessive all around, discs should survive for a long time, certainly 55k miles, if all you're doing is regular driving. Pads, yes, makes sense to replace them.

 

Thanks for the quick response Loki, I think you're right I'll get it into a Mazda garage and get them to take a look. I did get a tin of Cataclean down it (I forgot to mention) but that didn't make any difference.
From what the guy said when replacing the cat the threads in the sensor would tear hence needing to replace both?
Regarding the brakes, I guess I just got them done for peace of mind really, Halfords are also offering a brakes for life scheme where you pay for your 1st set of pads/shoes and they will replace in the future for free (even if you change vehicle) which I guess is pretty good but maybe the discs weren't essential.
But overall I certainly think I would be better off getting her into a an experienced Mazda Mechanic instead.

Many thanks Loki

 

If my conversion is right 440 euros = around 600$. With oem parts + labor its about the average price, I get good prices from a shop nearby and had 4 cross drilled rotors and sport pads for about 350 euros ''all EBC branded'' ... but then again no labor since i do my own stuff.
P0420 code is oxygen sensor related, could be cat also, i'd suggest a high flow one such as magnaflow for cheaper price & durability, OEM one is really big and don't last forever. Also verify the Air Pump's running great on cold starts, otherwise you'll melt the new cat really fast, especially OEM.
As far as 50 euros for clearing CEL, its ridiculous. Having a CEL is a sign something's not right, looking for the issue is the first thing a mechanic should do, suggesting about clearing a CEL without investigation might bring you even more issues @ long term.