Author Topic: Mazda 6 2008, trouble starting when engine hot. Error code P1378  (Read 3472 times)

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Offline Chimmy

  • S Class
  • *
  • Posts: 1
  • Engine: 2.0L
  • Fuel: Diesel
  • Transmission: Manual
  • Trim: TS2
  • Year: 2011
I have a 2008 Mazda 6 mzr-cd diesel that recently started to act up.
I got a CEL and pulled off the code P1378 FICM Supply Voltage Circuit Low.
It has been like this for a few weeks now, and it comes and goes.
And sometimes the car will not start while the engine is hot, and it has even stalled on me a couple of times while driving.
When the engine is cold, it usually starts up fine.

I took it to the garage, and they fixed a bad ground connection (just by the battery on the right side - apparently a known issue with these cars) and thought it would be fixed.
But CEL came back on once I started it.
They checked a couple more ground connections and measured voltage to injectors which looked fine.

Anyone else experienced this or have any suggestions as to what I can do?