Fault finding with the pre-cat 02 / Lambda sensor fault codes

Technical Area Engine, Transmission, Exhaust etc
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  1. My model of MX-5 is: __ NC1
  2. I’m based near: __ Cheltenham
  3. I’m looking for technical help or recommendations on: __Diagnosing issue with 02 / Lambda sensor

I bought my NC in May 23, 1 day after buying I had an EML come on and my mechanic diagnosed as the pre-cat 02 sensor was bad and this was replaced (luckily paid for by the selling garage).

Unfortunately the error(s) have come back, the EML codes are P0130 and P0134, first saw them on Sunday, cleared them and came back on today, cleared them again and came back on within 30 minutes.

I had a new catalytic converter fitted in February, if it helps with any sort of diagnosis. I have also checked and cleaned the MAF sensor as some Google searches say it could be related to the codes.

What sort of things should I be considering to try and diagnose the fault, to see it it is the sensor?

Thanks in advance

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check connections first to the sensors and inspect the harness make sure these haven’t been damaged

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Yes, give any connectors a jolly good wiggling.
May well do the trick.

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