Q: Car will not start. Will only move to ACC mode

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Car will not start after I depress the brake and push the start button. It only moves to ACC mode. Diagnosis showed a U0100 code. The mechanic says it has to do with a faulty BCM that should be replaced. Car starts after staying idle for some time.

My car has 22000 miles.
My car has an automatic transmission.

This relates to a faulty mass air flow sensor. This is a unit that monitors air intake into your engine as it is mixed with fuel prior to being injected into the motor. When this is not working properly, many issues can arise. Some of the causes for this not work are:

  • Faulty mass air flow sensor
  • Intake air leaks
  • Dirty mass air flow sensor
  • Dirty mass air filter
  • Mass air flow sensor harness is open or shorted
  • Mass air flow sensor circuit poor electrical connection

To have this scoped out further, I recommend having a certified professional from YourMechanic inspect the starting problem in person to verify whether or not you need a mass air flow sensor replacement.

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