MK3 Engine Management light

Hi,

So I bought a 2 litre mk3 mx5 not so long ago, and within a day the engine management light came up.  Took it to a garage and they told me it was the O2 Sensor in the Cat, so they took it out, flushed it out and the light was out.  Then 4 days later, it flashes up again.  This time I took it to a different garage who plugged it in, and it came up that it was the actual Cat converter itself, not the sensor in it. He has reset the light (basically putting the issue to sleep for a while), but I am quite confident it will appear again. 

Anybody had any similar experiences that they could help me with?

Did they specify what dtc code had been logged?

Prob first 02 sensor, don’t use cheap aftermarket ones…

if it’s the 2nd sensor give me a call…I have loads going spare

 

paul

They didn’t specify the code, all I know is one garage said it was the sensor, and another said it was the cat. I’m fairly sure it is the second sensor that the first garage said it was, i’m assuming this because they priced a new sensor around £80-£90 which is roughly the price of the second, with the first being significantly more expensive.

Any idea how much a new cat would roughly be???

And Paul thank you, that would be brilliant. As I say, if and more than likely when the light comes back on, i’ll get it diagnosed and see what the problem actually is.

When the Engine Management light came on on my Mk3.5, the code reader indicated that it was the EGR valve which was to blame. Good luck in solving your problem.

Suggest buying your own code reader. I bought a Bluetooth reader that connects with my phone for about £10 from Amazon.

Once you have the fault code there a lots of people on the forum who can advise what is wrong.

1 Like

If you have a Iphone you may want a wireless reader as they do not do bluetooth.

Otherwise a hand held job from ebay or amazon for say £15 will do the trick.

The socket in under the dash to the extreme right next to the right hand wing about 100 mm in from the front.

If it is EGR while a bit of a bugger to get at there is a lower cost solution than the Mazda price for the item;

https://www.mx5oc.co.uk/forum/yaf_postst67141_Exhaust-Gas-Recirc-Valve-on-the-NC-Engine.aspx

Thanks guys for the help, I’ll have a look online about getting myself a reader and see what that brings about. if I get any further I’ll let you know! 

It’s usually the upstream O2 sensor that fails. Mazda call it an AF (air/fuel) sensor.