P0624Generic code

P0624 Code: Fuel Cap Lamp Control Circuit

The P0624 code means there is a fault in the circuit that turns on the fuel cap warning light on the dash. The vehicle runs, but the driver may miss an important warning. Fix it so you are told when the cap is loose.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$5 to $400
Difficulty
Easy
System
Computer and Outputs
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0624 code means

The fuel cap warning light tells you the gas cap is loose or was left off. The computer turns it on directly, or sends the command to the instrument cluster over the communication network, and it monitors that the circuit responds.

On older vehicles the warning light is a bulb, and the fault is usually the burned out bulb itself or the wiring. On modern ones the cluster gets the command over the CAN network, and the P0624 code is usually a communication problem or a fault in the cluster itself.

Even if it looks like a minor fault, a warning light that does not work cannot warn you about real problems. Get it repaired.

Some vehicles warn about a loose cap with a dedicated light instead of the check engine light. If that light does not work, the driver will not know the cap was closed badly, and an EVAP leak code (P0455 or P0457) will eventually show up.

P0624 code symptoms

  • The light does not come on when you turn the key on (the bulb check).
  • The light is always on.

Likely causes of the P0624 code

  1. Burned out bulb or LED in the cluster. This is typical of older vehicles.
  2. Wiring between the computer and the cluster cut or shorted.
  3. Communication failure with the cluster on vehicles with a CAN network.
  4. Instrument cluster with an internal fault.

How to diagnose the P0624 code step by step

  1. Check whether the light comes on when you turn the key on.
  2. Use the scan tool to command the light if it allows that.
  3. Check for communication (U) codes.

How to fix the P0624 code

  • Replace the bulb or repair the wiring.
  • Repair the cluster if that turns out to be the problem.

Technical reference data

  • When you turn the key on, every warning light should come on for a few seconds.
  • Reference values: check the manufacturer data for your vehicle.

Brand-specific notes

On many modern vehicles you need a scan tool with access to the instrument cluster to diagnose this P0624 code.

Frequently asked questions about P0624

Can I drive with a P0624 code?
Yes, but without that warning. You will not be told if the gas cap is left loose, so tighten it until it clicks after every fill up.
Why is it important?
Because the light warns you about problems that can hurt the vehicle. A loose cap can also lead to an EVAP leak code later on.
Is it expensive to fix?
Usually not. A bulb or a wiring repair is cheap, and only a cluster repair pushes the cost up.
How much does it cost to fix P0624?
Between $5 and $400, depending on whether it is a bulb, the wiring or the instrument cluster.
What does the P0624 code mean?
It is a generic OBD2 code that means the circuit controlling the fuel cap warning light is not working properly.
What is the most common cause of P0624?
A burned out bulb on older vehicles, and a communication or cluster problem on newer ones.

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