Fault code P0131

Technical Area Engine, Transmission, Exhaust etc
2

Car had a P0131 code trigger EML.

Took car to Mazda dealer and had O2 sensor replaced.

P0131 code returned within 48hrs.

Further diagnostics done: now told CAT isn’t warming up properly (hot at front, cool at rear), however problem could be that or air/fuel sensor.

Before spending either £900 (CAT) or £500 (new sensor) advised to run cataclean through the system. Done with no change.

So big spend now potentially required! Suggestion from Mazda: sensor first (cheaper option) if this doesn’t resolve issue then replace CAT.

How is it possible they can‘t know which part requires changing?

I’ve already spent £400 on diagnostics and initial replacement O2 sensor, this didn’t resolve the issue! Now I’m told change air/fuel sensor £500 and if that doesn’t work change the CAT £900. If all these are done that’s £1800 and some of  parts may not have been needed in the first place (if fitting them made no difference).

Annoyed would be an understatement! How can Mazda not know what specifically is wrong???

Thoughts appreciated as I don’t have a bottomless pit of cash and yet I’m potentially spending money on parts that aren’t needed!

Seems ridiculous.

 

 

3

It can be difficult sometimes where there is just one generic fault code and several parts that could potentially be to blame.

In this instance P0131 appears to be specific to the precat lambda sensor, so a replacement should have resolved the issue.

I cannot see how the cat can be involved here and would be interested as to how the cat could possibly cause a P0131 error?

The Air/fuel sensor is actually a lambda(o2 sensor) on this car and the dealer has already replaced it. What is the other sensor they are proposing could be the problem, perhaps the post cat, diagnostic sensor?

You should have been charged for the initial diagnostic check and precat lambda sensor and that should have been an end to it.

        

4

As far as I understand I’ve had the pre-CAT 02 sensor replaced, and my assumption is the sensor they are now talking about is the post CAT one.
How this then correlates to a potentially dodgy CAT, I don’t know.
I can’t get clear answers hence my frustration, and lack of faith in what I’m being told.