What does code P1390 mean on Mazda vehicles?
The octane adjustment shorting bar is missing or the circuit is open, affecting ignition timing strategy.
OBD-II Code Mazda
P1390 — Mazda — Octane Adjust Shorting Bar Out or Circuit Open
The octane adjustment shorting bar is missing or the circuit is open, affecting ignition timing strategy.
Common symptoms
- Poor engine performance
- reduced power
Possible causes
- Missing or incorrect octane jumper
Initial recommendation
Install the correct octane adjustment shorting bar.
Safety notice
This information is for guidance only. Brand-specific codes may vary by model, year, engine, transmission and vehicle configuration. It does not replace a physical inspection or diagnosis by a qualified mechanic. If the vehicle is unsafe to operate, avoid driving it and seek professional inspection.
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