Should I buy a new gas cap?

Not for P0624 by itself — this code is about the indicator's electrical circuit, not the cap. A new cap is only worth trying if you also have leak codes like P0455 or P0457.

Why does my car even have a fuel cap light?

A loose cap is the single most common cause of EVAP leak codes, so some manufacturers added a dedicated indicator to say 'check the cap first' before drivers pay for diagnosis. Handy — when its own circuit works.

Can I ignore this one?

It's among the safest codes to deprioritize — nothing mechanical is wrong. Just know the check engine light will stay on (masking new problems) and the cap indicator can't do its job until fixed.

OBD-II trouble code

P0624: Fuel Cap Lamp Control Circuit

An electrical fault in the circuit that drives the "check fuel cap" indicator — the message or lamp itself, not necessarily anything wrong with the cap.

Quick facts

System: Powertrain
Category: Electrical / PCM
Severity: Low severity
Drivable: Usually safe to drive short-term
Repair cost range: $20 – $300
DIY difficulty: Beginner DIY

What does P0624 mean?

Some vehicles — many Fords, GM trucks, and others — have a dedicated "Check Fuel Cap" lamp or message that lights when the EVAP system detects the kind of large leak a loose gas cap causes. P0624 is not about the cap or the leak: it flags an electrical fault in the control circuit for that indicator itself. The computer tried to drive the lamp (or verify it) and saw an open, a short, or implausible feedback.

That distinction matters for diagnosis. If you also have leak codes (P0455, P0457), chase those first — the lamp circuit may be innocent. P0624 alone points at the indicator's wiring, the instrument cluster or message center, a connector, or occasionally the computer's lamp driver.

This is one of the most benign codes in the catalog: the engine, fuel system, and EVAP hardware are all presumed fine. The cost of ignoring it is that a genuinely loose cap in the future may not be able to tell you about itself — and the light stays on your dash in the meantime.

Common causes

Open or shorted wiring in the fuel cap lamp circuit
Instrument cluster or message center fault
Corroded connector between PCM/BCM and cluster
Failed indicator LED/bulb where discrete
PCM/BCM lamp driver fault (rare)

Symptoms

Check engine light on
Fuel cap indicator stuck on or never lighting
No drivability symptoms
EVAP system otherwise testing normal

Diagnostic steps

1.Scan for EVAP leak codes (P0455/P0456/P0457) — if present, diagnose the leak first; P0624 alone means a lamp-circuit fault.
2.Check whether the fuel cap indicator lights during the key-on bulb check.
3.Inspect wiring and connectors between the computer and the cluster/message center per the service diagram.
4.Test the cluster's indicator function with a scan tool output test where supported.
5.Repair wiring or service the cluster as found.
6.Clear codes and confirm the indicator behaves correctly at key-on.

Repair cost

$20 – $300

Often a connector or wiring repair at minimal cost. If the instrument cluster or message center needs service, costs rise toward the high end. There is rarely any reason to touch the fuel cap or EVAP hardware for this code alone.

Estimate your repair

Run the numbers for your vehicle

Open the Repair Cost Estimator with evap system repair preselected. Adjust labor rate and vehicle category to fit your situation.

Estimate your repair cost

DIY vs shop

This is a beginner-friendly repair. Common hand tools, a free afternoon, and a willingness to follow a procedure are usually enough. The risk of causing a bigger problem is low if you read up on your specific vehicle first.

Related codes

P0442 P0455 P0457