7 documented codes across 27 real diagnostics.
Glow plug circuits and the preheat control module. Seasonal: a cold-start complaint that only shows up in winter.
Ranked by how often we actually see them
- P0685, ECM/PCM power relay control circuit open
- P0675, Cylinder 5 glow plug circuit
- P0684, Glow plug control module to PCM communication circuit range/performance
- P0380, Glow plug or heater circuit A
- P0671, Cylinder 1 glow plug circuit
- P0672, Cylinder 2 glow plug circuit
- P0683, Glow plug control module to PCM communication circuit