The Acura RDX’s “check fuel cap” warning light is a notification that the vehicle has detected an issue with the fuel system.
…the most common reason for the check fuel cap warning is that the fuel cap is missing, not tightened enough, or damaged in some way.
The check fuel cap warning. doesn’t necessarily mean that the fuel cap has failed. Instead, there are several potential causes, such as an EVAP leak, fuel tank issues, or a loose or faulty fuel cap.
Check Fuel Cap Quick Info
| Definition | “Check Fuel Cap” |
| Symptoms | Fuel smell with no effect on how your RDX runs |
| Common Causes | Faulty gas cap, EVAP leak, fuel tank, or fuel neck leak |
| Breakdown Risk? | No |
| Repair Cost (Parts) | Usually under $100 (a gas cap is around $20 for a Acura-made unit) |
| Repair Difficulty | The most common fix is the gas cap, an easy repair. |
Check Fuel Cap Causes
Most of the Acura RDX “check fuel cap” causes are related to the gas cap. If it isn’t snugged down, it’ll cause the message. The first thing you should do is make sure the fuel cap is tight. If it’s not, you’ll need to tighten it until it clicks and drive a bit for the message to go away.
Gas Cap Issues
- Missing Fuel Cap– This often happens after a fill-up. With no fuel cap on, the message will populate right away. Replacing the fuel cap will clear the message.
- Loose Fuel Cap– When tightening a fuel cap, it needs to be snugged until there is a satisfying click. If that click is no longer being felt, it is time to replace it.
- Bad Fuel Cap– A rubber seal in the gas cap snugs against the fuel inlet. If this gasket has gone bad, fuel vapor can escape through the cracks, which causes the “Check Fuel Cap” light/warning message to appear.
EVAP Leak
Your fuel cap is part of your RDX’s larger Evaporative Emissions Control (EVAP) System. There is a certain amount of pressure in the tank.
Your Acura’s computer will throw the “Check Fuel Cap” warning when it detects that the pressure has changed enough that there’s likely a gas cap leak. Otherwise, it would have thrown an EVAP-related trouble code (most likely P0457).
“Check Fuel Cap” Diagnosis
To diagnose the issue, begin by examining the condition of your RDX’sfuel cap. It should be replaced if it is damaged, loose, or not properly sealed.
Check the Fuel Cap
To diagnose the issue, a technician will usually begin by examining the condition of the fuel cap. It should be replaced if it is damaged, loose, or not properly sealed.
Replacing or tightening it may not immediately turn off the fuel cap warning. Drive your RDX for a couple of days.
- Open the RDX’s fuel door.
- Twist the fuel cap to the left until it disengages from the fuel fill nozzle.
- Put the cap back on. Make sure the threads are lined up correctly and twist to the right until there is a click.
Inspect the Fuel Filler Neck and Tank
Then, inspect your Acura RDX’s fuel tank filler neck for any signs of damage or defects. If the fuel tank filler neck is leaking, it’ll need to be replaced.
Check for EVAP Codes
Finally, the technician can use a scan tool to check the venting system and verify that there are no problems with the EVAP system.
They can do a smoke test to find exactly where the EVAP system is leaking.
How Your Vehicle Knows to Turn on the Check Fuel Cap Warning
The check fuel cap indicator means that the ECM has detected a pressure leak in your RDX’s fuel tank.
If this has happened to your Acura RDX, make sure to put the cap back on somewhere safe. There is no immediate danger, and therefore no reason to pull off the road someplace dangerous to do this.
Common Questions
Q: Is it safe to drive with the “check fuel cap” warning?
A: Yes. There’s no breakdown risk. Your RDX will still run and drive just fine. The only thing you may notice is the slight smell of fuel (usually if your tank is full). You should still repair your RDX as soon as possible.
Q: How do you reset the “check fuel cap” warning?
To reset the “check fuel cap” warning, replace the fuel cap or fix the EVAP leak. Once you do so, the check fuel cap message will turn off.
Q: Is it Safe to Drive With a Bad Gas Cap?
It is safe to drive with the gas cap light on. It’s safer than pulling over to the side of the road. Your RDX has a built-in flapper valve that keeps the fuel in the tank even if the cap is missing.
Conclusion: Acura RDX “Check Fuel Cap”
Gas caps can and do go bad. They are not made to last the vehicle’s entire life (although some often do).
A bad or loose gas cap almost always causes the check fuel cap warning. It can sometimes indicate an EVAP leak. A “check fuel cap” message does not affect your Acura RDX’s ability to get yo where you need to go.