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2003 FORD THUNDERBIRD
3.9L DOHC V8 (280 hp)•FWD•AUTOMATIC•gas
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Repairs0Labor974Torque985Fluid14DTC1902Battery2Maintenance0Recalls0
P1390low severityPowertrain

Octane Adjust Pin Out of Self-Test Range

on 2003 Ford Thunderbird 3.9L DOHC V8 (280 hp) · FWD

What this code means

The octane adjust pin signal is not within the expected range during the self-test. This pin allows the PCM to adjust timing for different octane fuels.

Symptoms

  • Check Engine Light
  • Possible spark knock with low-octane fuel
  • Self-test failure

Common causes

  • Faulty octane adjust shorting bar
  • Wiring issue
  • PCM connector problem

Diagnostic steps

  1. Check octane adjust pin/shorting bar
  2. Inspect PCM connector
  3. Verify proper pin configuration for fuel grade

Repair notes

Check octane adjust shorting bar on PCM connector. Repair wiring if damaged.

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