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P1170moderate severityPowertrain

Bank to Bank Fuel Trim Offset

on 2000 GMC Safari 4.3L V6 Vortec · RWD

What this code means

The fuel trim values between the two engine banks differ more than allowed. This is a GM-specific code indicating an imbalance in air-fuel control between banks.

Symptoms

  • Check engine light on
  • Rough running
  • Uneven fuel economy

Common causes

  • Intake leak on one bank
  • Faulty O2 sensor on one bank
  • Dirty or failing injectors
  • MAF sensor fault

Diagnostic steps

  1. Compare bank 1 and bank 2 fuel trims
  2. Check for bank-specific vacuum leaks
  3. Inspect injectors per bank
  4. Test O2 sensors on each bank

Other Powertrain codes on this vehicle

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