P1251 – Fuel Cap Sensor Range/Performance
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Symptoms
- Intermittent cap warnings
- EVAP monitor not ready
- Check engine light
- Fuel odor
- Customer complaints
Causes
- Faulty sensor
- Cap not seating
- Connector issues
- Wiring resistance
- ECU interpretation fault
Diagnosis
- Check sensor output
- Inspect cap seal
- Inspect connector
- Check wiring
- Scan live data
Repair
- Replace fuel cap
- Replace cap sensor
- Repair wiring
- Clean connectors
- Update ECU software