P0455 on Acura: How to Diagnose & Fix
Evaporative Emission Control System Leak Detected (Gross Leak)
1 Acura model · 1 documented issue · $40-$150 repair
P0455 on Acura by model: symptoms, diagnosis and fix
2012-2013 RDX owners get a TIGHTEN FUEL CAP message and a check engine light for an EVAP leak, and the cap is tight. Acura issued service bulletin 14-006 covering the RDX and other Honda/Acura models: the original fuel cap's black gasket fails to seal reliably, so the EVAP system's leak monitor reports a leak that no amount of retightening will clear. Because the cap looks and feels fine, this is commonly chased with expensive smoke testing and purge-valve replacement before the cap is suspected. The EVAP fault will also block emissions-test readiness monitors.
Common Symptoms
- TIGHTEN FUEL CAP message on the dash
- Check engine light with EVAP leak code
- Code returns after retightening or replacing with a generic cap
- Emissions readiness monitors will not set
How to Fix
Replace the fuel cap with the updated OEM cap — the revised part carries a brown gasket rather than the original black one — per TSB 14-006, then clear the code and allow the EVAP monitor to run to completion. This is a low-cost fix and should be the first step before smoke testing. If the code returns with the revised cap installed, smoke-test the system for a cracked EVAP canister or a failed purge/vent valve, both documented on this platform. There is no recall.
Sources for this issue (2)
P0455 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0455 mean on a Acura?
P0455 stands for "Evaporative Emission Control System Leak Detected (Gross Leak)." This code means your car's evaporative emission (EVAP) system has detected a large (gross) leak, so fuel vapors that should be sealed inside the fuel and vapor system are escaping into the atmosphere. The EVAP system captures gasoline vapors from the tank and routes them to the engine to be burned instead of polluting the air, and the computer periodically pressure- or vacuum-tests this sealed system. A gross leak almost always points to something obvious and easy, like a loose, missing, or bad gas cap, rather than a deep mechanical failure. It rarely affects how the car drives, but it should be fixed to pass emissions and stop wasting fuel vapor. On Acura it is documented across 1 model: RDX.
What are the most common causes of P0455?
The most common causes of P0455 are: Loose, missing, or improperly tightened gas cap, Worn, cracked, or failed gas cap seal, Cracked or disconnected EVAP/vapor hose, Damaged or missing fuel filler neck seal, Faulty EVAP purge valve stuck open, Failed EVAP vent valve, Cracked or damaged charcoal canister. The specific cause varies by vehicle.
How much does it cost to fix P0455 on a Acura?
Published repair estimates on Acura range from $40 to $150 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.