What Does P0624 Mean?
The PCM/ECM has detected a fault in the fuel cap lamp control circuit. This circuit controls the dashboard indicator that alerts the driver when the fuel cap is loose, missing, or not sealing properly. A circuit fault means the warning lamp may not illuminate when there is actually a fuel cap issue, or it may stay on continuously even when the cap is properly installed. This is an emissions-related circuit that helps catch EVAP system leaks.
Common Causes
30%
Open or short in the fuel cap lamp circuit wiring
25%
Faulty fuel cap lamp or LED in the instrument cluster
20%
PCM/ECM output driver failure for fuel cap lamp
15%
Instrument cluster communication issue (if lamp is controlled via data bus)
10%
Loose fuel cap actually triggering the EVAP system fault concurrently
Diagnostic Steps
1
Remove and re-seat the fuel cap, ensuring it clicks at least three times. Clear the code and drive to see if it returns. This rules out an actual loose cap triggering related issues.
2
With the scan tool, command the fuel cap lamp on and off using bi-directional controls if available. Verify the lamp responds to commands.
3
Check the fuel cap lamp circuit for continuity from the PCM to the instrument cluster. Inspect connectors at both ends for corrosion or damage.
4
Measure the voltage at the fuel cap lamp driver circuit at the PCM connector — it should change state when the PCM commands the lamp on vs. off.
5
If the lamp does not respond but the PCM is commanding correctly and wiring is good, the instrument cluster may need replacement or repair.
Estimated Repair Cost
$20 - $250
Parts + labor, varies by vehicle and location
The PCM/ECM has detected a fault in the fuel cap lamp control circuit. This circuit controls the dashboard indicator that alerts the driver when the fuel cap is loose, missing, or not sealing properly. A circuit fault means the warning lamp may not illuminate when there is actually a fuel cap issue,...
The most common cause of P0624 (Fuel Cap Lamp Control Circuit) is: Open or short in the fuel cap lamp circuit wiring
Typical repair costs for P0624 range from $20 to $250, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is a low-risk code. The vehicle is safe to drive. The only concern is that you may not be alerted to a loose fuel cap, which could cause fuel vapor emissions and potentially trigger additional EVAP-related DTCs. Check your fuel cap manually on occasion until the circuit is repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0624 to identify the root cause.
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Quick Info
Category
Powertrain
System
EVAP / Instrument System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
