P2408 Fuel Cap Sensor/Switch Circuit

P2408 is the general circuit code for a sensor or switch that tells the engine computer whether the fuel cap or filler is closed. It is set when that circuit shows a fault not narrowed down to low, high, plausibility or dropout, which are P2410, P2411, P2409 and P2412. No manufacturer publicly documents this code; most systems infer the cap state from pressure instead. Ford's OBD summary, for example, detects a missing or loose cap (P0457) when the tank does not pull down past -8 inH2O within 30 s after refuelling, lights a Check Fuel Cap lamp and shows a capless-filler message. CARB lets makers skip the MIL for a detected cap leak if a separate warning lamp exists. The vehicle drives normally; the cap and wiring should be checked.

Likely causes

Symptoms

• Check engine light or fuel cap warning
• EVAP leak test may be skipped

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, newtonnet.co.uk.