Is there a way to find a fault code without taking it to a mechanic, so I can google the issue?
What mileage?
Have you had the timing chain tensioner replaced at all?
Whilst you can - and as mentioned Torque will likely give you some of the generic fault codes, in a lot of cases you will still need dealer level diagnostics (e.g. BMW DIS) or a 3rd party equivalent (bavarian technic or bimcom?), in order to correctly interpret the cause of those faults.
Mileage is ~78K
I don't think the timing chain tensioner has been replaced(?).
I wasn't suggesting to buy them, just that using Torque is unlikely to give you a code that gives you an instant fix. It likely will give you a generic error such as "P0011 Camshaft Position A - Timing Over-Advanced", whereas a "dealer level diagnostic", would likely give you more information to narrow it downThat appears quite costly. If the fault presented by dealer level diagnostics means the mini has to go in to the shop there would be nothing gained.
78,000 My money is on an O2 sensor
78,000 My money is on an O2 sensor
Same, bank 2.
Same, bank 2.
It will be saved in the ECU as previous fault. You can either take it in and replace whatever caused it or wait for it to come back on again before taking it in.
Timing Chain problems are unfortunately a common issue on the Cooper S.
Surely it only has Bank 1 Sensor 1 & 2?
Do you mean post cat?