2009 Nissan Frontier - Ongoing problem is not the O2 sensor

When I dismount my vehicle, sometimes there is no contact or the engine runs but without starting.
When that happens, I have to try several times before the engine starts up.
I think it could be an electrical defect in the switch! Is it possible?
Is this a recurring problem for this vehicle?
My car have 140 000 km.
I explained this problem to my mechanic and he changed the oxygen sensor and it did not change my problem.
Thanks for following me.

First please restate your post. “ engine runs but without starting“. Does this mean cranks but does not start?
Is the check engine light on? If so have the codes read and post them here.
And, I think you need a better mechanic, problems need to be diagnosed first. Changing the O2 sensor without a diagnosis makes no sense.

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I’m presuming you used a computer language translation for that sentence. You’ll get better results here if ask someone who is more fluent in English to translate it for you.

Could well be the crankshaft sensor is bad, especially if your Frontier has the 2.5 engine. It will cause the symptoms you describe, especially in hot weather, and it will not always set an engine malfunction code. Its also at the right age to go bad. Best to change it and the camshaft sensor at the same time. Best ones to get would be genuine Nissan as some of the real cheap replacements can be problematic. Otherwise get NTK or Hitachi ones which should be high quality. Bonne chance avec la réparation!