My mazda 6 (2004) was running fine. CEL was on for 4 years with an EVAP issue. Mechanic told me it was a sensor issue, and it was never fixed. (ODB2 P2404)


Yesterday had a lot of snow, today went to start, and the engine turns over fine, but the car wouldn't start.


Tried 4 separate times, same thing. (Approx 5 mins apart)


Plugged in ODB2 reader, just the P2404 code.


Asked my wife to start it while I looked under the hood, and she started it.


While it was running I plugged in the ODB2 reader, and got U0100, U0101, U0121, P2404.


So now I'm still concerned as to why the car wouldn't start, but then with nothing actually being done, aside from removing the engine cover, it started.


I cleared the codes, and started the car, and nothing has come up.


Any suggestions as to what could cause a temporary issue like this? Just concerned it is a symptom of a larger issue.


Thanks for any suggestions.
Joe