Powertrain, generic · Computer and auxiliary outputs

P0624 Fuel Cap Lamp Control Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Despite its neighbours, P0624 has nothing to do with the alternator: it is the control circuit of the 'check fuel cap' warning lamp of the evaporative system. Ford's evaporative monitor lights such a lamp when, after refuelling, the tank cannot be pulled into vacuum – a gross leak or missing cap (P0457) – and turns it off once the cap is secured; not every vehicle has this lamp. The module driving the lamp (engine or body module, depending on the vehicle) can monitor its output for open or short circuits. No manufacturer document available to us uses P0624 itself. The lamp is only a hint; the leak is reported with the check engine light as P0455/P0457, so P0624 itself is practically emission neutral under CARB. The lamp then never lights or stays on, and a loose cap is no longer indicated.

Likely causes

Wire or connector to the warning lamp or instrument cluster
Bulb/LED or instrument cluster faulty
Output driver in the engine or body module

Symptoms

  • Fuel cap lamp never lights or stays on
  • A loose cap is no longer indicated
  • No driving symptoms

Repair estimate

DifficultyEasyDIY possible
Parts and labour€0–300
Time0.3–1.5 h

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

Parts involved

fuel cap warning lampinstrument clusterlamp control circuit

Related codes

P0457P0455P0623

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