P1129 – Excessive Fuel Pressure
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Symptoms
- Rough idle
- Poor fuel economy
- Black smoke
- Hesitation
- Check engine light
Causes
- Faulty fuel pressure regulator
- Stuck return line
- Leaking injector
- Fuel pump issue
- ECU issue
Diagnosis
- Test fuel pressure
- Inspect regulator
- Inspect injectors
- Scan live data
- Inspect return line
Repair
- Replace regulator
- Fix return line
- Replace injectors
- Replace fuel pump
- Update ECU