My car has an intermittent warning that comes on. Once every 3-6 weeks it’ll beep at me but it doesn’t appear to impact the car’s running in the slightest.
I bought a bluetooth ODB2 reader (mentioned by cp above) and either use Torque Free on my phone or MultiECUScan on my laptop to read and clear the code.
Every time it comes up it’s the same code relating to the Cam/Phase position sensor. I’ve replaced the sensor and checked the all the wires/connectors around it and it’s still the same.
I’ve learned to live with it, if I don’t clear the code with the ODB2 reader, it clears itself after a couple of days anyway, so would be just as ‘hidden’ from a potential buyer anyway…
It once came on when being MOTd, but the guy said if he cleared it and it didn’t come straight back on that would be fine.
Long story short… Look on the owners site for your car and see what they advise.